Update to latest versions of actions, and simplify elm-publish-action setup

[dillonkearns]

Mostly boring updates to reduce deprecation noise.

I also simplified the elm-publish-action setup. Using dry-run: true is redundant - the workflow is:

1. Check to see if it is in a publishable state
2. If not, give an error
3. If it is publishable, AND the elm.json has a bumped version, AND we're on the main/master branch, THEN run elm publish (creating a git tag as needed)

[jfmengels]

Thanks 😊