Issue #15301: skip new test method so Windows builtbots stop failing.

Lib/test/test_os.py

@@ -867,6 +867,7 @@ class MakedirTests(unittest.TestCase):
         os.makedirs(path, mode=mode, exist_ok=True)
         os.umask(old_mask)
 
+    @unittest.skipUnless(hasattr(os, 'chown'), 'test needs os.chown')
     def test_chown_uid_gid_arguments_must_be_index(self):
         stat = os.stat(support.TESTFN)
         uid = stat.st_uid