assertDictContainsSubset was removed in Python 3.11

[tirkarthi]

Issue Summary

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

Steps to Reproduce

twilio-python/tests/unit/jwt/test_jwt.py:        self.assertDictContainsSubset({
twilio-python/tests/unit/jwt/test_client_validation.py:        self.assertDictContainsSubset({
twilio-python/tests/unit/jwt/test_client_validation.py:        self.assertDictContainsSubset({

[eshanholtz]

This issue has been added to our internal backlog to be prioritized (Reference ID: DI-1915). Pull requests and +1s on the issue summary will help it move up the backlog.