Fixed undefined error when running rails g impressionist(undefined method `timestamped_migrations')

[ihatov08]

The following error occurred when running rails g impressionist, so I fixed it.

/usr/local/bundle/gems/activerecord-7.1.3.2/lib/active_record/dynamic_matchers.rb:22:in `method_missing': undefined method `timestamped_migrations' for ActiveRecord::Base:Class (NoMethodError)

ActiveRecord.timestamped_migrations is now used when the major version of rails is 7 or higher.