Add tests for non-E2E Python tests on different versions

[UpGado]

We make the claim that we support Python 3.5+, however, it would be good to verify that in our CI. We can add matrix tests that run tests on Python 3.5, 3.6, 3.7, 3.8. Those tests have to run quickly, so they cannot include the Docker environment. Thus, we will have to mock the authenticator functionality in Python to allow the tests to run. This is not bad in itself because it allows us to isolate testing the Python SDK from the authenticator