Mark macOS-only failure

Lib/test/test_platform.py

@@ -253,6 +253,10 @@ class PlatformTest(unittest.TestCase):
                 self.assertEqual(res[2], 'PowerPC')
 
 
+    # TODO: RUSTPYTHON
+    if sys.platform == "darwin":
+        test_mac_ver = unittest.expectedFailure(test_mac_ver)
+
     # TODO: RUSTPYTHON
     @unittest.expectedFailure
     @unittest.skipUnless(sys.platform == 'darwin', "OSX only test")