Use filename when printing pending migrations

Filename provides the path, whereas basename does not. It makes
sense to show the full filename, since migrations can be stored across
directories in multi-db apps.

Author: adrianna-chang-shopify

activerecord/lib/active_record/migration.rb

@@ -160,7 +160,7 @@ def detailed_migration_message(pending_migrations)
         message += "You have #{pending_migrations.size} pending #{pending_migrations.size > 1 ? 'migrations:' : 'migration:'}\n\n"
 
         pending_migrations.each do |pending_migration|
-          message += "#{pending_migration.basename}\n"
+          message += "#{pending_migration.filename}\n"
         end
 
         message