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