docs: updating compatible Python versions

[clatapie]

Description

As title says.

Checklist

• I have visited and read Develop PyMAPDL.
• I have tested my changes locally
• I have added necessary documentation or updated existing documentation.
• I have followed the PyMAPDL coding style guidelines.
• I have added appropriate unit tests that also ensure the minimal coverage criteria.
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved to the PR if any.
• I have assigned this PR to myself.
• I have marked this PR as draft if it is not ready to be reviewed yet.
• I have made sure that the title of my PR follows Commit naming conventions (e.g. feat: adding new MAPDL command)

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.92%. Comparing base (853daba) to head (633ff92).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3572      +/-   ##
==========================================
- Coverage   86.93%   86.92%   -0.02%     
==========================================
  Files         187      187              
  Lines       14616    14619       +3     
==========================================
+ Hits        12707    12708       +1     
- Misses       1909     1911       +2     

[germa89]

Good catch!