Update docs to reflect Python requirement

[Mark2000]

• Tickets addressed: Python 3.9 is not supported under some conditions #723 and others
• Merge strategy: Merge (no squash)

Description

Users have been running into issues with Python ≤3.9 for a while now. While we never formally deprecated support for 3.9, Basilisk has only compiled on ≥3.10 for a few months now. I don't think it's worth anybody's time to track down when 3.9 support was lost, so I propose updating the documentation and conanfile to reflect the 3.10 requirement.

Verification

N/A.

Documentation

Primarily documentation changes.

Future work

N/A

[schaubh]

Howdy @Mark2000, actually, the CI test scripts are running against Python 3.9 on both the Linux and Windows build? They complete without issues. What issues are you running into?

[Mark2000]

This person (#723) could not get Basilisk to compile on linux (Ubuntu 22.08) until upgrading to 3.10. I had the same experience on the university's cluster (RedHat 7.9).

[schaubh]

That issue appears to be with Ubuntu 22.08 using python 3.9, not python 3.9 per say. On another fork they updated their test build to use the newer version of Ubuntu and also upgrade python from 3.9 to 3.10.

What we should do is update the Linux build instructions to specify that Ubuntu 22.08 requires Python 3.10? We can also add an additional CI test build action where we build both with Python 3.9 on 20.04, and Python 3.10 on 22.08?

If we are adding additional CI checks, it would be nice to add a 3rd Linux test build (faster than Windows test build) to build with 22.08 and Python 3.11? This way we are running CI test builds for python 3.9, 3.10 and 3.11.

[Mark2000]

I'll run some experiments tomorrow since I'll be around my linux machine. I suspect that Python 3.9 allows for some combination of dependencies that is invalid, but Python 3.10 somehow prevents that bad combination from being possible.

[schaubh]

You can see the CI build scripts in basilisk/.github/workflows/pull-request.yml. Assuming your Linux testing of my statements works out, we can make this PR be to explain Python requirements for the two versions of Ubuntu, and the updated CI builds would be a separate PR I could work on.