Add functionality to run unit tests, if any

I was looking over b9ps's project setup and it's pretty cool.  Some projects actually have unit tests set up, and it would be awesome to run them from our workflows and actions.

https://github.com/blowfishpro/B9PartSwitch/blob/e282eb138340aa0ea2c2926cb48e9c6a1e408d93/.github/workflows/build-and-test.yml#L55