CI builds for Windows via GitHub Actions

[bajtos]

This is a follow-up for #5110, where we configured CI builds to run on GitHub Actions, but did not manage to pass all tests on Windows.

My current understanding is that GitHub Actions is running CI scripts with non-TTY (and possibly empty) stdin stream, thus triggering TTY-related issues as described in #4425 (comment) and follow-up comments. The discussion further continues in #4607, which is the issue tracking this specific problem.

In #5110, @achrinza added https://github.com/Yuri6037/Action-FakeTTY to our workflow to enable a fake TTY. This fixed the problem on MacOS, but not for Windows :(

We need to further investigate this problem and either find a way how to setup TTY or fix #4607.