Include the Rails version in the database schema

This is from the "Upgrading Ruby on Rails" guide:

https://guides.rubyonrails.org/upgrading_ruby_on_rails.html#rails-version-is-now-included-in-the-active-record-schema-dump

As for the changes on the columns, see this comment from a core Rails
maintainer: https://github.com/rails/rails/issues/44571#issuecomment-1056131789