Remove test for multiprocessing on Mac

With Python 3.7 support now dropped, there are no versions of Python on
macOS that we expect to support with multiprocessing again.  There's no
guarantee that the hypothetical Python 10.11 (???) that this test was
previously checking would be any more valid than existing versions.

test/python/tools/test_parallel.py

@@ -48,13 +48,6 @@ def test_windows_parallel_default(self):
             parallel_default = get_platform_parallel_default()
             self.assertEqual(parallel_default, False)
 
-    def test_mac_os_supported_version_parallel_default(self):
-        """Verifies the parallel default for macOS."""
-        with patch("sys.platform", "darwin"):
-            with patch("sys.version_info", (10, 11, 0, "final", 0)):
-                parallel_default = get_platform_parallel_default()
-                self.assertEqual(parallel_default, True)
-
     def test_mac_os_unsupported_version_parallel_default(self):
         """Verifies the parallel default for macOS."""
         with patch("sys.platform", "darwin"):