Update Node version range in CI, use modern Node version

[rdmurphy]

Closes #42.

Hello! I saw the post on Mastodon and the organizing issue and decided to try and help if I can! I did a few things here, mostly with the goal of establishing a solid foundation for testing future changes against modern versions of Node.

• Happy to undo this, but I've made the CI action run against every commit instead of just master and PRs against master. I think this will put the matrix testing to better use (and because PRs are made of commits, those will still get tested!)
• I've bumped the matrix up to v18, v20 and v22. v20 is the current LTS version, but it goes into maintenance mode in 15 days and v22 will take its place.
• I've updated the action versions, and now actions/setup-node@v4 will use caching to speed up installs.
• I've bumped the working version of Node to v22 in the project. Could see an argument for using v20 instead, but did so for the same reason as above!
• The package-lock.json appeared to be out of sync because every install would update it locally. I updated the CI command to use npm ci instead of npm install which would catch this mismatch. Definitely some dependencies that could stand to be updated, but all tests are passing, which is nice.

If any/all of this doesn't feel like it makes sense, just let me know! (Or feel free to close it if I'm way off base.)

[RoelN]

Thank you @rdmurphy!

@Ryuno-Ki, can I bother you for a quick review? It looks good to me and it makes sense, but I'd appreciate another pair of eyes on this!

[RoelN]

@rdmurphy If you agree with those suggestions, then I'll wait for the changes and then we can merge this puppy! 🐶