Add windows support

[fizyk]

• Run Tests on Windows CI automatically
• Make code compatible with windows
  • there's no poll in select
  • socket.AF_UNIX on windows
  • no killpg on windows
  • exiting process returns same exit code as signal on windows, while on linux it's -sig
  • lack of ps aux

[biyani701]

Adding this patch in conftest.py helps move forward on windows

if sys.platform == "win32":
    import psutil

    def _killpg(pid, sig=None):
        try:
            parent = psutil.Process(pid)

            # Kill children first
            for child in parent.children(recursive=True):
                try:
                    child.kill()
                except psutil.NoSuchProcess:
                    pass

            parent.kill()

        except psutil.NoSuchProcess:
            pass

    os.killpg = _killpg  # type: ignore[attr-defined]