Run test_posix on Windows #111912

When I searched for a place for tests for gh-111841, I have found that they already exist, but in test_posix which is skipped on Windows.

The simplest way is to make test_posix running on Windows. It turned out that most tests are already compatible with Windows, except this test and yet one test that tests for Posix-specific constants.

Linked PRs

• gh-111912: Run test_posix on Windows #111913
• [3.12] gh-111912: Run test_posix on Windows (GH-111913) #111953
• [3.11] gh-111912: Run test_posix on Windows (GH-111913) #111954