chore: Add Ruby 3.2 and JRuby 9.3 and 9.4 to CI. Update checkout action versions

[petergoldstein]

Updates the CI matrix so it includes Ruby 3.2, JRuby 9.3, and JRuby 9.4 Also updates the checkout action version to eliminate the Node 12 warning on builds.

Checklist

• [x] I acknowledge that all my contributions will be made under the project's license
• [x] I have made a material change to the repo (functionality, testing, spelling, grammar)
• [x] I have read the Contribution Guidelines and my PR follows them
• [x] I have titled the PR appropriately
• [x] I have updated my branch with the main branch
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I have added the necessary documentation about the functionality in the appropriate .md file
• [x] I have added inline documentation to the code I modified

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