feat: automated releasing

[Justintime50]

Description

Now that we have an API Key saved to GitHub Actions for RubyGems, we can use it to automate releasing this lib. Once a GitHub Release has been created (which automatically creates an accompanying tag), GitHub Actions will build and publish the library to RubyGems.

Testing

I've used this workflow for other repos for years.

Pull Request Type

Please select the option(s) that are relevant to this PR.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement (fixing a typo, updating readme, renaming a variable name, etc)