Drop Python 3.9 support

[tomvothecoder]

Description

• Closes [DevOps]: Drop Python 3.9 support #896

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

If applicable:

• New and existing unit tests pass with my changes (locally and CI/CD build)
• I have added tests that prove my fix is effective or that my feature works
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have noted that this is a breaking change for a major release (fix or feature that would cause existing functionality to not work as expected)

[xylar]

@tomvothecoder, this will not be part of 3.0.0, correct?

[tomvothecoder]

@xylar Are we still supporting Python 3.9 in the next E3SM Unified? If we are, I'll need to revert this merge and keep it open for later.

[xylar]

Yes, we have to. We only have python 3.9 and 3.10 because of the cdat madness we still have to support. I don't feel good about dropping python 3.9 and having only python 3.10.

[tomvothecoder]

Yes, we have to. We only have python 3.9 and 3.10 because of the cdat madness we still have to support. I don't feel good about dropping python 3.9 and having only python 3.10.

Thanks for clarifying, I should have reached out first before getting to excited to merge this PR. I just reverted the merge.

I thought we were dropping Python 3.9 support based on this message from you on 10/1/24 in the e3sm-unified-testing-releases Slack:

The latest release of pyproj has just dropped support for python 3.9:
https://github.com/pyproj4/pyproj/releases/tag/3.7.0
This likely means that E3SM-Unified 1.11.0 will only be able to support python 3.10 to accommodate both this new pyproj and CDAT

But I saw you're going to use 3.6.1 for python <3.10 and 3.7.0 for python >=3.10 here.

In any case, I'm looking forward to getting rid of Python 3.9 and CDAT too.

[xylar]

Oh, I forgot I had said that back in October but I think we do want to keep it if we can.