Allow running Que on Rails 7.1

[texpert]

QueAdapter has been removed from ActiveJob in Rails 7.1, so now a Rails 7.1 app fails to start with the cannot load such file -- active_job/queue_adapters/que_adapter (LoadError) even if not using ActiveJob with Que.

This PR is enabling running Que on Rails 7.1 not requiring que/active_job/extensions.

[ZimbiX]

Sorry, I didn't realise this would be an issue in removing the Que adapter from Rails! 😬 I really should have tested that before giving the go ahead for rails/rails#46005 in rails/rails#45899.

Thanks for having a go at fixing this. However, according to Que's tests (which it turns out has incorrect gem version specificity, so Que's tests against Rails 7.0 are actually testing 7.1), it looks like this change hasn't fixed the issue:

<internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:37:in `require': cannot load such file -- active_job/queue_adapters/que_adapter (LoadError)
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:37:in `require'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/activejob-7.1.0/lib/active_job/queue_adapters.rb:138:in `const_get'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/activejob-7.1.0/lib/active_job/queue_adapters.rb:138:in `lookup'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/activejob-7.1.0/lib/active_job/queue_adapter.rb:51:in `queue_adapter='
	from /home/runner/work/que/que/spec/spec_helper.rb:13:in `<top (required)>'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:37:in `require'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:37:in `require'
	from /home/runner/work/que/que/spec/que/active_job/extensions.job_extensions_spec.rb:3:in `<top (required)>'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:37:in `require'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:37:in `require'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/rake-13.0.6/lib/rake/rake_test_loader.rb:21:in `block in <main>'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/rake-13.0.6/lib/rake/rake_test_loader.rb:6:in `select'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/rake-13.0.6/lib/rake/rake_test_loader.rb:6:in `<main>'

I read the logic you've added as 'skip the require on Rails 7.1' - I think whatever fix we work out should apply to Rails 7.1+, not just 7.1.

Also, I don't think requiring that file is the issue. I think the extensions are still needed... This autoloading of a nonexistent class might be more the issue.

[ZimbiX]

I've fixed the tests' Rails version specificity in #402, and rebased this PR, also adding testing against Rails 7.1.

[ZimbiX]

I've taken a different direction, so thought that warranted a new PR =) #403