Set up CI through GitHub Actions

[wkearn]

At the moment, we mainly want to verify that the package builds correctly on different operating systems.

I don't think we really have automated tests yet, but once we have those, we can run them through CI as well.

This is related to

• 26

• 25

• 23

[wkearn]

28 implements a CI workflow through GitHub Actions.

As mentioned there, I think we can also add

• [ ] A code format check
• [ ] Linting
• [ ] Automated tests

to the workflow. @Teschl: I think you could add whatever checks you ran for #23 to address the first two points. The last one requires some automated tests, which we will have to set up.