Address deprecation of ActiveRecord::Base.connection in Rails 7.2

[joshuay03]

Context: rails/rails#51349

Ensures that applications using config.active_record.permanent_connection_checkout = :disallowed are supported from Rails 7.2 onwards. This was what this PR started as, but this would require a significant API change looking at how the #start and #clean APIs are used.

Addresses the deprecation of ActiveRecord::Base.connection in favour of ActiveRecord::Base.lease_connection as of Rails 7.2.

There's one more usage of .connection but that seems to be getting removed in #101.

[ghiculescu]

I think this usage also needs to be updated:

database_cleaner-active_record/lib/database_cleaner/active_record/truncation.rb

Line 33 in aafa5b2

@connection ||= ConnectionWrapper.new(connection_class.connection)

Otherwise you get a "Called deprecated ActiveRecord::Base.connection method." deprecation warning.

[joshuay03]

@ghiculescu Addressed 👍🏽

[etagwerker]

@joshuay03 @ghiculescu Looks good, thank you!