Windows CI doesn't exit sometimes

[tomwhite]

Even when all the tests pass, the build doesn't exit immediately and will be cancelled a few hours later (e.g. https://github.com/cubed-dev/cubed/actions/runs/11974180543/job/33384715251?pr=621).

[tomwhite]

This is happening because Lithops is not exiting properly - see #635.

I've excluded the Windows from the Lithops tests in #640 so this doesn't cause failures, but I'll leave this open.