assertDictContainsSubset was removed in Python 3.11

[Karthikeyan Singaravelan]

The deprecated aliases were removed in Python 3.11 in python/cpython#28268

test/test_nose/test_flaky_nose_plugin.py:        self.assertDictContainsSubset(
test/test_flaky_decorator.py:        self.assertDictContainsSubset(