New error in Solid Queue 0.8.1 seems related to how we setup our test DB.

SolidQueue v0.8+ merged all the migrations into a single schema file
that is automatically loaded onto the DB on a Rails app. They suggest a
separate DB, which AR will handle automatically by copying over this
single file schema to the app, and to use on the same DB one would have
to manually move the schema to a migration and execute it.

For our case, all we care about is to have SolidQueue schema / tables
loaded onto our test DB. We do that by manually loading the lib's schema
file via Active Record. We still execute migrations afterwards, even
though it's a no-op for current SolidQueue, if they need to make new
schema changes in the future, they'll come in the form of migrations.

This way we can test both minimum and whatever "current/latest" is.
(currently v1.0)

Update GH matrix to skip unsupported Ruby versions on Rails 7.2 as well,
(main Gemfile for now) since it requires Ruby 3.1+.

We already have a few other requires that were needed there to get tests
running, we can keep this new one there too, as it should not be a
problem in runtime within a normal Rails environment. (and if it happens
to be, we'll learn about it soon enough.)