Fix timestamped_migrations method call since deprecated

[phChun]

Per Rails 7.x,

DEPRECATION WARNING: ActiveRecord::Base.timestamped_migrations is deprecated and will be removed in Rails 7.1.
Use `ActiveRecord.timestamped_migrations` instead.   

This method was removed in Rails 7.1, breaking the sorcery installer. Following the guidance from the deprecation warning, the fix listed above works.