Avoid deprecated TestCase functions in unit tests. (#76678)

* Avoid deprecated TestCase functions in unit tests.
* Add assertRaisesRegex for Python 2.7.
* Fix indentation.

test/units/plugins/cache/test_cache.py

@@ -185,9 +185,9 @@ class TestFactCache(unittest.TestCase):
         # See https://github.com/ansible/ansible/issues/18751
         # Note no fact_connection config set, so this will fail
         with mock.patch('ansible.constants.CACHE_PLUGIN', 'json'):
-            self.assertRaisesRegexp(AnsibleError,
-                                    "Unable to load the facts cache plugin.*json.*",
-                                    FactCache)
+            self.assertRaisesRegex(AnsibleError,
+                                   "Unable to load the facts cache plugin.*json.*",
+                                   FactCache)
 
     def test_update(self):
         self.cache.update({'cache_key': {'key2': 'updatedvalue'}})