Add Ruby 3.1 to the CI matrix

[petergoldstein]

In addition to the necessary changes to the workflow.yml - added 3.1 and excluding unsupported ActiveRecord/Ruby combinations, the following changes were made:

1. Updated gemfiles to modern versions of rake and rspec - this was necessary to get specs running. There are some deprecation warnings, but everything runs green
2. Use YAML safe_load with an aliases true argument - As Psych 4.0+ now calls safe_load for load, we make this call explicit and add the necessary aliases argument for it to pass.

[petergoldstein]

Everything runs green - https://github.com/petergoldstein/hair_trigger/actions/runs/1958440193

[jenseng]

Thanks @petergoldstein!

[petergoldstein]

@jenseng As Ruby 3.2 is just about to come out, it may be worth revisiting the supported matrix, trimming some old versions, and adding 3.2 preemptively (making any necessary changes to the code base)

[jenseng]

Good call, thanks @petergoldstein 👍