Run tests on Rails 7.2

[tomgi]

This PR is to show that the tests fail on current master because of deprecations in Rails 7.2.

It's not intended to be merged.

  1) Error:
Que::ActiveRecord::Connection::JobMiddleware#test_0001_should clear connections to secondary DBs between jobs:
NoMethodError: undefined method `clear_active_connections!' for SecondDatabaseModel:Class
Did you mean?  clear_validators!
    /opt/hostedtoolcache/Ruby/3.1.6/x64/lib/ruby/gems/3.1.0/gems/activerecord-7.2.1.2/lib/active_record/dynamic_matchers.rb:22:in `method_missing'
    /home/runner/work/que/que/spec/que/active_record/connection_spec.rb:42:in `block (2 levels) in <top (required)>'

  2) Error:
Que::ActiveRecord::Connection::JobMiddleware#test_0002_shouldn't clear connections to secondary DBs between jobs if run_synchronously is enabled :
NoMethodError: undefined method `clear_active_connections!' for SecondDatabaseModel:Class
Did you mean?  clear_validators!
    /opt/hostedtoolcache/Ruby/3.1.6/x64/lib/ruby/gems/3.1.0/gems/activerecord-7.2.1.2/lib/active_record/dynamic_matchers.rb:22:in `method_missing'
    /home/runner/work/que/que/spec/que/active_record/connection_spec.rb:42:in `block (2 levels) in <top (required)>'

Fixed in #423, which also includes changes from this PR.

Close this PR after the above is merged.