[CI] remove Python 3.9 from and add 3.13 to CRON CI

[orbeckst]

Since 2.8.0 we do not officially support Python 3.9 anymore and hence 3.9 jobs do not need to run in CRON CI:

mdanalysis/.github/workflows/gh-ci-cron.yaml

Line 242 in ac145ec

python-version: ["3.9", "3.10", "3.11", "3.12"]

However, we are now supporting 3.13 so this should be added.

(And check if there are any other places where the Python versions need to be updated.)

[orbeckst]

duplicate of #4806