Rework testing on Windows in CI

[facelessuser]

The old action for using msys2 is currently broken. Take a look at some alternatives such as https://github.com/msys2/setup-msys2.

[facelessuser]

I won't let this hold up the next release as I imagine it is going to take me some time to figure how to configure this new action to work.