Pipeline fails in Python 3.6

[grisu48]

The CI pipeline for python 3.6 fails because python 3.6 is deprecated:

______________________ ERROR collecting tests/test_gce.py ______________________
tests/test_gce.py:1: in <module>
    from ocw.lib.gce import GCE
ocw/lib/gce.py:4: in <module>
    from google.oauth2 import service_account
/opt/hostedtoolcache/Python/3.6.15/x64/lib/python3.6/site-packages/google/oauth2/service_account.py:77: in <module>
    from google.auth import _service_account_info
/opt/hostedtoolcache/Python/3.6.15/x64/lib/python3.6/site-packages/google/auth/_service_account_info.py:22: in <module>
    from google.auth import crypt
/opt/hostedtoolcache/Python/3.6.15/x64/lib/python3.6/site-packages/google/auth/crypt/__init__.py:43: in <module>
    from google.auth.crypt import rsa
/opt/hostedtoolcache/Python/3.6.15/x64/lib/python3.6/site-packages/google/auth/crypt/rsa.py:20: in <module>
    from google.auth.crypt import _cryptography_rsa
/opt/hostedtoolcache/Python/3.6.15/x64/lib/python3.6/site-packages/google/auth/crypt/_cryptography_rsa.py:22: in <module>
    import cryptography.exceptions
/opt/hostedtoolcache/Python/3.6.15/x64/lib/python3.6/site-packages/cryptography/__init__.py:28: in <module>
    stacklevel=2,
E   cryptography.utils.CryptographyDeprecationWarning: Python 3.6 is no longer supported by the Python core team. Therefore, support for it is deprecated in cryptography and will be removed in a future release.