black formatting for test

python/ctsm/test/test_sys_run_tower.py

@@ -87,7 +87,6 @@ def test_ad_site(self):
         # Test use of base case root.
         # Test for using prism?
 
-
     def test_plumber_site(self):
         """
         This test specifies a site to run a default plumber AD case with
@@ -109,6 +108,7 @@ def test_plumber_site(self):
         # assert that AR-SLu directories were created during setup
         self.assertTrue("AR-SLu" in glob.glob(self._tempdir + "/AR-SLu*")[0])
 
+
 if __name__ == "__main__":
     unit_testing.setup_for_tests()
     unittest.main()