gh-103661: Skip failing test on Windows.

[jaraco]

• Issue: importlib/test_metadata_api fails on Windows buildbots #103661

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @jaraco for commit cd3b0b7 🤖

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

[jaraco]

The Windows buildbots are passing, indicating this change has the intended effect. Other buildbots are failing, but that's presumably due to something else.