Add a no-op in ZipFixture teardown.

Seems to prevent the failure by giving the zip resource time to be garbage collected.

Author: jaraco

Lib/test/test_importlib/metadata/fixtures.py

@@ -374,6 +374,8 @@ def setUp(self):
         # Add self.zip_name to the front of sys.path.
         self.resources = contextlib.ExitStack()
         self.addCleanup(self.resources.close)
+        # workaround for #138313
+        self.addCleanup(lambda: None)
 
 
 def parameterize(*args_set):