Drop Python 3.7 support and update CI envs
Python 3.7 will be EOL in 3 months, so before the next release.
- Update the Python versions in the CI images
- Bump the docker base image from focal to jammy to test against a newer stack. This triggers new deprecation warnings which we need to disable for now.
- Bump the old docker based image to from buster to bullseye, moving from Python 3.7 to 3.9.