Remove unused Python3.9 uses from Github action CI

[pankajastro]

This PR clean unused Python3.9 uses from Github action CI

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[Copilot]

Pull Request Overview

This PR removes a redundant Python 3.9 exclusion from the GitHub Actions CI test matrix. The exclusion was preventing the Python 3.9 + Airflow 2.7 combination from being tested, but since Python 3.9 is not included in the test matrix to begin with, this exclusion entry serves no purpose.

• Removed Python 3.9 with Airflow 2.7 exclusion entry from the test matrix
• Removed associated comment explaining the temporary nature of the exclusion

Comments suppressed due to low confidence (1)

.github/workflows/test.yml:57

• Python 3.9 is declared as a supported version in pyproject.toml (line 11: requires-python = \">=3.9\", line 24 classifier, and line 170 in hatch test matrix) but is not included in the CI test matrix. Consider either adding Python 3.9 to the test matrix or removing it from the supported versions in pyproject.toml to align the project's stated support with actual testing coverage.

        python-version: ["3.10", "3.11", "3.12"]

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[tatiana]

When did we remove Python 3.9 support..? My understanding is that we agreed to not do this change for now: #2035. I discussed with @yetudada and she was happy for us to continue support Python 3.9 for now as well. The Python 3.9 are the fastest tests to run in our CI and they have not caused mantainance overhead, so I'd like to see them being re-added.

[tatiana]

I just saw it was removed by mistake in this PR:
a9fca6a#diff-faff1af3d8ff408964a57b2e475f69a6b7c7b71c9978cccc8f471798caac2c88

We should re-add it, and skip it only for the latest versions of Airflow that don't support it.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.81%. Comparing base (b58778b) to head (5166136).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2117   +/-   ##
=======================================
  Coverage   97.81%   97.81%           
=======================================
  Files          92       92           
  Lines        5961     5961           
=======================================
  Hits         5831     5831           
  Misses        130      130           

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[pankajkoti]

On the contrary, I agree with @pankajastro's thoughts in comment. My opinion is that we should be aggressive on dropping dbt and Python versions that have reached their EOL.

[tatiana]

I just checked the two utilisation sources we have, Astro Cloud customers, and Scarf. And I agree for us to remove Python 3.9 support.

The main reasoning:

• We currently have 0.4% of Astro customers who have Cosmos installed using Python 3.9.
• Within the Scarf data, we see the top 10 python_version utilised, and all of them are Python 3.10 or higher

More details in the slack discussion.

[pankajkoti]

@pankajastro I believe it's important that we highlight in our user facing docs and Changelog that starting Cosmos 1.12.0 we're dropping support for Python 3.9. Would be nice if you could add a PR for the same when possible.

[pankajastro]

@pankajastro I believe it's important that we highlight in our user facing docs and Changelog that starting Cosmos 1.12.0 we're dropping support for Python 3.9. Would be nice if you could add a PR for the same when possible.

yes, created followup PR: #2118