No need to inherit from object in Python 3

tests/test_cli.py

@@ -29,7 +29,7 @@ from yamllint import cli
 from yamllint import config
 
 
-class RunContext(object):
+class RunContext:
     """Context manager for ``cli.run()`` to capture exit code and streams."""
 
     def __init__(self, case):

tests/test_config.py

@@ -121,7 +121,7 @@ class SimpleConfigTestCase(unittest.TestCase):
         self.assertEqual(c.rules['hyphens'], False)
 
     def test_validate_rule_conf(self):
-        class Rule(object):
+        class Rule:
             ID = 'fake'
 
         self.assertFalse(config.validate_rule_conf(Rule, False))