This method wasn't making use of the que_jobs.args index and was
performing badly on large datasets.

GIN indexes don't support the '=' operator, but support existence '?'
and containment '@>' among others. To make use of the index the query
has to check for containment of a subset document rather than match a
value within the document directly.

QueJob#by_job_args is already querying in this way; this change makes
QueJob#by_job_class consistent with it.

Context:

https://www.postgresql.org/docs/9.6/datatype-json.html#JSON-INDEXING

Given a jsonb column "data" indexed as follows:
  CREATE INDEX data_index ON table USING GIN (data);

And with data in this format:
  {
    "name": "Melbourne",
    "type": "City"
  }

This query will make use of the index:
  SELECT data FROM table WHERE data @> '{"name": "Melbourne"}';

But this one will not:
  SELECT data FROM table WHERE data->>'name' = "Melbourne";

Improve `QueJob#by_job_class` performance.

Ability to disable listen/noify on CLI resulting in jobs
being picked up purely from polling. We have seen issues
with listen/notify usage at scale.

List que-prometheus in readme

The Gemfile that's supposed to test Rails 7.0 was running Rails 7.1 🤦

```
Installing activejob 7.1.0
```

https://github.com/que-rb/que/actions/runs/6456183723/job/17525155590?pr=401#step:5:87

…-in-spec-gemfiles

Fix specificity of Rails versions in spec gemfiles

(Tests not yet passing)

This no longer exists in Rails, but is still needed. I simply copied the class from the [removal PR](rails/rails#46005), and removed the unnecessary comments, and adjusted the formatting slightly.

(Tests not yet passing)

I'd thought we'd need to now use `ActiveJob::Base.queue_adapter = ActiveJob::QueueAdapters::QueAdapter.new` rather than `ActiveJob::Base.queue_adapter = :que`, but it seems that by keeping the adapter class namespace unchanged, we can still use the latter.

…equire_job_options_kwarg?

We don't need to support old versions of Que in the adapter anymore! Que's codebase always uses the latest Que =P

I considered removing & inlining Que::ActiveJob::WrapperExtensions::ClassMethods#enqueue into our Rails 7.1+ QueAdapter, but it still needs to exist in place for support for older versions of Rails =\ Keeping it in place conditionally based on the Rails version would be [a bit complex](#399 (comment)), and so perhaps not an improvement.

Allow que to be started without listen/notify

Support Rails 7.1+ by adding ActiveJob Que adapter removed from Rails

…ction

Don't clear ActiveRecord connections when run_synchronously is enabled

See this comment for more info: https://github.com/que-rb/que/pull/403\#issuecomment-1764134027

Temporarily restict rails version to 7.1.0 for 7.1 tests