Update deprecator horizon for 7.3

This change was never released on 7.1, so we can't remove it on 7.2.

Author: rafaelfranca

activesupport/lib/active_support/core_ext/module/attr_internal.rb

@@ -25,7 +25,7 @@ class << self
     def attr_internal_naming_format=(format)
       if format.start_with?("@")
         ActiveSupport.deprecator.warn <<~MESSAGE
-          Setting `attr_internal_naming_format` with a `@` prefix is deprecated and will be removed in Rails 7.2.
+          Setting `attr_internal_naming_format` with a `@` prefix is deprecated and will be removed in Rails 7.3.
 
           You can simply replace #{format.inspect} by #{format.delete_prefix("@").inspect}.
         MESSAGE