The CircleCI tests have not been updated for quite some time.

The CI Containers are also testing on Python 3.7, 3.8 and 3.9. All but Python 3.9 are End-of-Life (EOL). And, it will be EOL by October of this year.

Current Pull Requests show:

You’re using a deprecated Docker convenience image. Upgrade to a next-gen Docker convenience image.

And, this is a full explanation of the CircleCI Deprecation:
https://discuss.circleci.com/t/legacy-convenience-image-deprecation/41034