Run test suite automatically

[digitaldogsbody]

Add a GitHub action to run the test suite on commit to main & PR

[digitaldogsbody]

This is done and worked ok, but I borked up the triggers so it only ran on the first opening of each PR, and not if you added any further commits. Rectified in 80e4648 but hasn't had the opportunity to run yet. As soon as it does and works ok, then I will close this ticket 😀