Add Ruby 3.1 and ruby-head to CI

[petergoldstein]

Description

This PR adds Ruby 3.1 and ruby-head to CI.

As part of that change it fixes a few keyword argument issues in the specs - three specs were failing because the arguments passed to with were being intepreted as keyword arguments. Wrapping them in explicit hashes resolved those failures.

I also observed a pre-existing failure to post to Coveralls (for all Rubies) that I did not address.

Completed Tasks

• I have read the Contributing Guide.
• The pull request is complete (implemented / written).
• Git commits have been cleaned up (squash WIP / revert commits).
• I wrote tests and ran bundle exec rake locally (if code is attached to PR).

[lsegal]

This was resolved by #1424 and #1433, but thank you for the contribution!

Note that ruby-head will not be added since we historically had gottten a lot of regression based failures that I do not have enough bandwidth to work around.