add workflow to test pygenesys using gh actions

[yardasol]

This PR adds a workflow to auto-test pygenesis via GitHub Actions.

[yardasol]

I just now saw that this is already set up via circleci. I will close this PR for now, but if we ever want to switch over to GH actions, someone can reopen this PR and try to merge (if it works)

[samgdotson]

I think we should reopen this, actually. I'm not familiar with testing via github actions vs circle ci. Though, I would like to add a test coverage badge to the readme, which I think needs to be done with github actions. Definitely a worthwhile conversation!

[samgdotson]

I think this is extremely helpful. It won't replace circle ci just yet, but definitely good to include. A couple of notes:

1. Is temoa installed in the right place? Does it matter? (see comment)
2. Does temoa need to be installed? It's only necessary if users want to run a temoa simulation -- this may be helpful if I create integration tests using an example model, but right now it serves no purpose.
3. The .yml file is gobbledygook to me. I would love an explanation offline, sometime.

[samgdotson]

I think this will download Temoa to pygenesys\pygenesys\temoa (per the log file), which is not really where temoa should live in relation to pygenesys.

[yardasol]

The block you've highlighted doesn't really effect where Temoa is downloaded to. Instead, it indicates that changes to files on the given paths will trigger this workflow.

[samgdotson]

is it possible to also run-on windows latest?

[yardasol]

It's very possible, would need to slightly readjust some of the syntax, but very easy to do.

[samgdotson]

Suggested change

	runs-on: ubuntu-latest
	runs-on: ${{ matrix.os }}
	strategy:
	matrix: [ubuntu-latest, windows-latest, macOS-latest]

I think this should do it.

[yardasol]

We'll want to have a cache for each os.

[samgdotson]

@yardasol the windows build fails because windows doesn't support the default solver (CBC) for temoa. I don't think our CI should include a temoa build since we only have unit tests. We can introduce a separate check if/when integration tests are introduced. Since pygenesys is separate from temoa, the latter could make breaking changes for their project which would show up as failed checks for this repo -- which isn't our job to handle imo. Thoughts?

[yardasol]

I think that's reasonable.