Update all Migration version references

Migration version references has been updated 2 times in less than 3
weeks (rails#41894, rails#42113).

I'd not want to receive the same tweaks in the near future.

Author: kamipo

activerecord/README.rdoc

@@ -140,7 +140,7 @@ This would also define the following accessors: <tt>Product#name</tt> and
 
 * Database agnostic schema management with Migrations.
 
-    class AddSystemSettings < ActiveRecord::Migration[6.0]
+    class AddSystemSettings < ActiveRecord::Migration[7.0]
       def up
         create_table :system_settings do |t|
           t.string  :name

activerecord/lib/active_record/associations.rb

@@ -1780,7 +1780,7 @@ def belongs_to(name, scope = nil, **options)
         # The join table should not have a primary key or a model associated with it. You must manually generate the
         # join table with a migration such as this:
         #
-        #   class CreateDevelopersProjectsJoinTable < ActiveRecord::Migration[6.0]
+        #   class CreateDevelopersProjectsJoinTable < ActiveRecord::Migration[7.0]
         #     def change
         #       create_join_table :developers, :projects
         #     end

activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb

@@ -278,7 +278,7 @@ def #{column_type}(*names, **options)
     # Inside migration files, the +t+ object in {create_table}[rdoc-ref:SchemaStatements#create_table]
     # is actually of this type:
     #
-    #   class SomeMigration < ActiveRecord::Migration[6.0]
+    #   class SomeMigration < ActiveRecord::Migration[7.0]
     #     def up
     #       create_table :foo do |t|
     #         puts t.class  # => "ActiveRecord::ConnectionAdapters::TableDefinition"

activerecord/lib/active_record/migration.rb

@@ -20,7 +20,7 @@ def initialize(message = nil)
   # For example the following migration is not reversible.
   # Rolling back this migration will raise an ActiveRecord::IrreversibleMigration error.
   #
-  #   class IrreversibleMigrationExample < ActiveRecord::Migration[6.0]
+  #   class IrreversibleMigrationExample < ActiveRecord::Migration[7.0]
   #     def change
   #       create_table :distributors do |t|
   #         t.string :zipcode
@@ -38,7 +38,7 @@ def initialize(message = nil)
   #
   # 1. Define <tt>#up</tt> and <tt>#down</tt> methods instead of <tt>#change</tt>:
   #
-  #  class ReversibleMigrationExample < ActiveRecord::Migration[6.0]
+  #  class ReversibleMigrationExample < ActiveRecord::Migration[7.0]
   #    def up
   #      create_table :distributors do |t|
   #        t.string :zipcode
@@ -63,7 +63,7 @@ def initialize(message = nil)
   #
   # 2. Use the #reversible method in <tt>#change</tt> method:
   #
-  #   class ReversibleMigrationExample < ActiveRecord::Migration[6.0]
+  #   class ReversibleMigrationExample < ActiveRecord::Migration[7.0]
   #     def change
   #       create_table :distributors do |t|
   #         t.string :zipcode
@@ -228,7 +228,7 @@ def initialize
   #
   # Example of a simple migration:
   #
-  #   class AddSsl < ActiveRecord::Migration[6.0]
+  #   class AddSsl < ActiveRecord::Migration[7.0]
   #     def up
   #       add_column :accounts, :ssl_enabled, :boolean, default: true
   #     end
@@ -248,7 +248,7 @@ def initialize
   #
   # Example of a more complex migration that also needs to initialize data:
   #
-  #   class AddSystemSettings < ActiveRecord::Migration[6.0]
+  #   class AddSystemSettings < ActiveRecord::Migration[7.0]
   #     def up
   #       create_table :system_settings do |t|
   #         t.string  :name
@@ -376,7 +376,7 @@ def initialize
   #   bin/rails generate migration add_fieldname_to_tablename fieldname:string
   #
   # This will generate the file <tt>timestamp_add_fieldname_to_tablename.rb</tt>, which will look like this:
-  #   class AddFieldnameToTablename < ActiveRecord::Migration[6.0]
+  #   class AddFieldnameToTablename < ActiveRecord::Migration[7.0]
   #     def change
   #       add_column :tablenames, :fieldname, :string
   #     end
@@ -402,7 +402,7 @@ def initialize
   #
   # Not all migrations change the schema. Some just fix the data:
   #
-  #   class RemoveEmptyTags < ActiveRecord::Migration[6.0]
+  #   class RemoveEmptyTags < ActiveRecord::Migration[7.0]
   #     def up
   #       Tag.all.each { |tag| tag.destroy if tag.pages.empty? }
   #     end
@@ -415,7 +415,7 @@ def initialize
   #
   # Others remove columns when they migrate up instead of down:
   #
-  #   class RemoveUnnecessaryItemAttributes < ActiveRecord::Migration[6.0]
+  #   class RemoveUnnecessaryItemAttributes < ActiveRecord::Migration[7.0]
   #     def up
   #       remove_column :items, :incomplete_items_count
   #       remove_column :items, :completed_items_count
@@ -429,7 +429,7 @@ def initialize
   #
   # And sometimes you need to do something in SQL not abstracted directly by migrations:
   #
-  #   class MakeJoinUnique < ActiveRecord::Migration[6.0]
+  #   class MakeJoinUnique < ActiveRecord::Migration[7.0]
   #     def up
   #       execute "ALTER TABLE `pages_linked_pages` ADD UNIQUE `page_id_linked_page_id` (`page_id`,`linked_page_id`)"
   #     end
@@ -446,7 +446,7 @@ def initialize
   # <tt>Base#reset_column_information</tt> in order to ensure that the model has the
   # latest column data from after the new column was added. Example:
   #
-  #   class AddPeopleSalary < ActiveRecord::Migration[6.0]
+  #   class AddPeopleSalary < ActiveRecord::Migration[7.0]
   #     def up
   #       add_column :people, :salary, :integer
   #       Person.reset_column_information
@@ -504,7 +504,7 @@ def initialize
   # To define a reversible migration, define the +change+ method in your
   # migration like this:
   #
-  #   class TenderloveMigration < ActiveRecord::Migration[6.0]
+  #   class TenderloveMigration < ActiveRecord::Migration[7.0]
   #     def change
   #       create_table(:horses) do |t|
   #         t.column :content, :text
@@ -534,7 +534,7 @@ def initialize
   # can't execute inside a transaction though, and for these situations
   # you can turn the automatic transactions off.
   #
-  #   class ChangeEnum < ActiveRecord::Migration[6.0]
+  #   class ChangeEnum < ActiveRecord::Migration[7.0]
   #     disable_ddl_transaction!
   #
   #     def up
@@ -698,7 +698,7 @@ def initialize(name = self.class.name, version = nil)
     # and create the table 'apples' on the way up, and the reverse
     # on the way down.
     #
-    #   class FixTLMigration < ActiveRecord::Migration[6.0]
+    #   class FixTLMigration < ActiveRecord::Migration[7.0]
     #     def change
     #       revert do
     #         create_table(:horses) do |t|
@@ -717,7 +717,7 @@ def initialize(name = self.class.name, version = nil)
     #
     #   require_relative "20121212123456_tenderlove_migration"
     #
-    #   class FixupTLMigration < ActiveRecord::Migration[6.0]
+    #   class FixupTLMigration < ActiveRecord::Migration[7.0]
     #     def change
     #       revert TenderloveMigration
     #
@@ -768,7 +768,7 @@ def down
     # when the three columns 'first_name', 'last_name' and 'full_name' exist,
     # even when migrating down:
     #
-    #    class SplitNameMigration < ActiveRecord::Migration[6.0]
+    #    class SplitNameMigration < ActiveRecord::Migration[7.0]
     #      def change
     #        add_column :users, :first_name, :string
     #        add_column :users, :last_name, :string
@@ -796,7 +796,7 @@ def reversible
     # In the following example, the new column +published+ will be given
     # the value +true+ for all existing records.
     #
-    #    class AddPublishedToPosts < ActiveRecord::Migration[6.0]
+    #    class AddPublishedToPosts < ActiveRecord::Migration[7.0]
     #      def change
     #        add_column :posts, :published, :boolean, default: false
     #        up_only do

activerecord/lib/active_record/model_schema.rb

@@ -489,7 +489,7 @@ def content_columns
       # when just after creating a table you want to populate it with some default
       # values, eg:
       #
-      #  class CreateJobLevels < ActiveRecord::Migration[6.0]
+      #  class CreateJobLevels < ActiveRecord::Migration[7.0]
       #    def up
       #      create_table :job_levels do |t|
       #        t.integer :id

guides/bug_report_templates/active_record_migrations_gem.rb

@@ -29,7 +29,7 @@
 class Payment < ActiveRecord::Base
 end
 
-class ChangeAmountToAddScale < ActiveRecord::Migration[6.0]
+class ChangeAmountToAddScale < ActiveRecord::Migration[6.1]
   def change
     reversible do |dir|
       dir.up do

guides/bug_report_templates/active_record_migrations_main.rb

@@ -28,7 +28,7 @@
 class Payment < ActiveRecord::Base
 end
 
-class ChangeAmountToAddScale < ActiveRecord::Migration[6.0]
+class ChangeAmountToAddScale < ActiveRecord::Migration[7.0]
   def change
     reversible do |dir|
       dir.up do

guides/source/active_record_basics.md

@@ -368,7 +368,7 @@ database that Active Record supports using `rake`. Here's a migration that
 creates a table:
 
 ```ruby
-class CreatePublications < ActiveRecord::Migration[6.0]
+class CreatePublications < ActiveRecord::Migration[7.0]
   def change
     create_table :publications do |t|
       t.string :title

guides/source/active_record_migrations.md

@@ -34,7 +34,7 @@ history to the latest version. Active Record will also update your
 Here's an example of a migration:
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration[6.0]
+class CreateProducts < ActiveRecord::Migration[7.0]
   def change
     create_table :products do |t|
       t.string :name
@@ -71,7 +71,7 @@ If you wish for a migration to do something that Active Record doesn't know how
 to reverse, you can use `reversible`:
 
 ```ruby
-class ChangeProductsPrice < ActiveRecord::Migration[6.0]
+class ChangeProductsPrice < ActiveRecord::Migration[7.0]
   def change
     reversible do |dir|
       change_table :products do |t|
@@ -86,7 +86,7 @@ end
 Alternatively, you can use `up` and `down` instead of `change`:
 
 ```ruby
-class ChangeProductsPrice < ActiveRecord::Migration[6.0]
+class ChangeProductsPrice < ActiveRecord::Migration[7.0]
   def up
     change_table :products do |t|
       t.change :price, :string
@@ -128,7 +128,7 @@ $ bin/rails generate migration AddPartNumberToProducts
 This will create an appropriately named empty migration:
 
 ```ruby
-class AddPartNumberToProducts < ActiveRecord::Migration[6.0]
+class AddPartNumberToProducts < ActiveRecord::Migration[7.0]
   def change
   end
 end
@@ -150,7 +150,7 @@ $ bin/rails generate migration AddPartNumberToProducts part_number:string
 will generate
 
 ```ruby
-class AddPartNumberToProducts < ActiveRecord::Migration[6.0]
+class AddPartNumberToProducts < ActiveRecord::Migration[7.0]
   def change
     add_column :products, :part_number, :string
   end
@@ -166,7 +166,7 @@ $ bin/rails generate migration AddPartNumberToProducts part_number:string:index
 will generate the appropriate `add_column` and [`add_index`][] statements:
 
 ```ruby
-class AddPartNumberToProducts < ActiveRecord::Migration[6.0]
+class AddPartNumberToProducts < ActiveRecord::Migration[7.0]
   def change
     add_column :products, :part_number, :string
     add_index :products, :part_number
@@ -183,7 +183,7 @@ $ bin/rails generate migration RemovePartNumberFromProducts part_number:string
 generates
 
 ```ruby
-class RemovePartNumberFromProducts < ActiveRecord::Migration[6.0]
+class RemovePartNumberFromProducts < ActiveRecord::Migration[7.0]
   def change
     remove_column :products, :part_number, :string
   end
@@ -199,7 +199,7 @@ $ bin/rails generate migration AddDetailsToProducts part_number:string price:dec
 generates
 
 ```ruby
-class AddDetailsToProducts < ActiveRecord::Migration[6.0]
+class AddDetailsToProducts < ActiveRecord::Migration[7.0]
   def change
     add_column :products, :part_number, :string
     add_column :products, :price, :decimal
@@ -218,7 +218,7 @@ $ bin/rails generate migration CreateProducts name:string part_number:string
 generates
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration[6.0]
+class CreateProducts < ActiveRecord::Migration[7.0]
   def change
     create_table :products do |t|
       t.string :name
@@ -244,7 +244,7 @@ $ bin/rails generate migration AddUserRefToProducts user:references
 generates the following [`add_reference`][] call:
 
 ```ruby
-class AddUserRefToProducts < ActiveRecord::Migration[6.0]
+class AddUserRefToProducts < ActiveRecord::Migration[7.0]
   def change
     add_reference :products, :user, foreign_key: true
   end
@@ -262,7 +262,7 @@ $ bin/rails generate migration CreateJoinTableCustomerProduct customer product
 will produce the following migration:
 
 ```ruby
-class CreateJoinTableCustomerProduct < ActiveRecord::Migration[6.0]
+class CreateJoinTableCustomerProduct < ActiveRecord::Migration[7.0]
   def change
     create_join_table :customers, :products do |t|
       # t.index [:customer_id, :product_id]
@@ -291,7 +291,7 @@ $ bin/rails generate model Product name:string description:text
 will create a migration that looks like this
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration[6.0]
+class CreateProducts < ActiveRecord::Migration[7.0]
   def change
     create_table :products do |t|
       t.string :name
@@ -319,7 +319,7 @@ $ bin/rails generate migration AddDetailsToProducts 'price:decimal{5,2}' supplie
 will produce a migration that looks like this
 
 ```ruby
-class AddDetailsToProducts < ActiveRecord::Migration[6.0]
+class AddDetailsToProducts < ActiveRecord::Migration[7.0]
   def change
     add_column :products, :price, :decimal, precision: 5, scale: 2
     add_reference :products, :supplier, polymorphic: true
@@ -605,7 +605,7 @@ to reverse. You can use [`reversible`][] to specify what to do when running a
 migration and what else to do when reverting it. For example:
 
 ```ruby
-class ExampleMigration < ActiveRecord::Migration[6.0]
+class ExampleMigration < ActiveRecord::Migration[7.0]
   def change
     create_table :distributors do |t|
       t.string :zipcode
@@ -660,7 +660,7 @@ is wise to perform the transformations in precisely the reverse order they were
 made in the `up` method. The example in the `reversible` section is equivalent to:
 
 ```ruby
-class ExampleMigration < ActiveRecord::Migration[6.0]
+class ExampleMigration < ActiveRecord::Migration[7.0]
   def up
     create_table :distributors do |t|
       t.string :zipcode
@@ -703,7 +703,7 @@ You can use Active Record's ability to rollback migrations using the [`revert`][
 ```ruby
 require_relative "20121212123456_example_migration"
 
-class FixupExampleMigration < ActiveRecord::Migration[6.0]
+class FixupExampleMigration < ActiveRecord::Migration[7.0]
   def change
     revert ExampleMigration
 
@@ -721,7 +721,7 @@ is later decided it would be best to use Active Record validations,
 in place of the `CHECK` constraint, to verify the zipcode.
 
 ```ruby
-class DontUseConstraintForZipcodeValidationMigration < ActiveRecord::Migration[6.0]
+class DontUseConstraintForZipcodeValidationMigration < ActiveRecord::Migration[7.0]
   def change
     revert do
       # copy-pasted code from ExampleMigration
@@ -883,7 +883,7 @@ Several methods are provided in migrations that allow you to control all this:
 For example, this migration:
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration[6.0]
+class CreateProducts < ActiveRecord::Migration[7.0]
   def change
     suppress_messages do
       create_table :products do |t|
@@ -1052,7 +1052,7 @@ to add or modify data. This is useful in an existing database that can't be dest
 and recreated, such as a production database.
 
 ```ruby
-class AddInitialProducts < ActiveRecord::Migration[6.0]
+class AddInitialProducts < ActiveRecord::Migration[7.0]
   def up
     5.times do |i|
       Product.create(name: "Product ##{i}", description: "A product.")