feat: run tests for simple cabal projects

[saep]

Description of changes

I've added the ability to run tests on simple cabal projects (such as https://github.com/neovimhaskell/nvim-hs).

Since I'm using nix flakes, I typically don't have any extraneous build tools (such as stack) installed. That's why I added the check for a stack executable. This should be backwards compatible and allow people like me to use cabal instead of stack on normal projects without a project.cabal.

Things done

• Tested, as applicable:
  • Added plenary specs: Is the pipeline capable of running cabal test?
  • Manually
• Updated CHANGELOG.md (if applicable).
• Fits CONTRIBUTING.md

[mrcjkb]

Thanks for the contribution!

[mrcjkb]

To answer your question about adding plenary specs: I haven't had time to figure out how best to write integration tests for this plugin yet.
It's definitely on my agenda. But until then, we have to make do with manual tests 😞

[mrcjkb]

It looks like the changelog entry is missing?

[mrcjkb]

Lgtm. Thanks for all the work!

[mrcjkb]

@all-contributors please add @saep for code

[allcontributors]

@mrcjkb

I've put up a pull request to add @saep! 🎉