Modernize build

[pbrisbin]

Don't commit stack.yaml.lock files

These are important for reproducible builds, but Haskell libraries are
source-distributed and built on install, so they have no effect there.

They also bring a minor downside when using a tool like stack-all.

Refactor stack resolver files

• Name them stack-ltsX, so we don't need to maintain minor changes
• Add lts23 and lts24 files
• Maintain stack.yaml as a symlink to latest resolver

Don't run CI on pushes to main

This CI doesn't produce or block anything useful, so it's just a waste
of build minutes.

Modernize CI

• Use stack-action/generate (no need for separate nightly)
• Use newer stack-action with caching built-in
• Use haskell-actions

[pbrisbin]

See https://github.com/freckle/github-vending-machine/pull/161 for the corresponding branch protection requirements change.

[chris-martin]

Going to update the release step too?

      - if: steps.tag.outputs.tag
        run: stack upload --pvp-bounds lower .
        env:
          HACKAGE_KEY: ${{ secrets.HACKAGE_UPLOAD_API_KEY }}
          STACK_YAML: stack-lts12.yaml

[pbrisbin]

I always forget that!

[pbrisbin]

Oh, I don't have to. This repository uses our older stack-upload-action. Now that stack upload supports API keys, we don't really need that action anymore but one thing it is currently doing is automatically selecting the minimum resolver file. So, until I update this to move away from that (and to semantic release), this'll just work.