Update CI

[calebhearth]

Move to another CI - GitHub maybe? - and update the metrix for currently supported Rubies and Railses

[notapatch]

Hi Caleb

I saw you talk about this library on "How to Open Source.

This is the first github actions workflow for a Gem I've done. The code comes from an example and runs through a matrix of Rubies and two OS's (ubuntu and mac os). .

I don't see how you can run it through different Rails versions??

I've done a number of runs in Github actions on my fork - you'll need to enable github actions on this repo before you see anything

I had some fun and accidentally put the PR's to your library when I meant to send it to mine, so you'll see I opened and closed two PRs!