Add support for Python 3.14 and drop EOL 3.9

[hugovk]

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Description

Please explain the changes you made here.

Python 3.14 is out: https://discuss.python.org/t/python-3-14-0-final-is-here/104210

Python 3.9 is EOL: https://discuss.python.org/t/the-final-python-3-9-security-fix-release-is-out/104666

https://devguide.python.org/versions/

Checklist

• Created tests which fail without the change (if possible)
• All tests passing
• Added a changelog entry
• Extended the README / documentation, if necessary

[codecov-commenter]

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (1f34057) to head (3da4c49).
⚠️ Report is 38 commits behind head on master.
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Additional details and impacted files

@@            Coverage Diff            @@
##            master      #185   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            8         8           
  Lines          287       296    +9     
  Branches        54        34   -20     
=========================================
+ Hits           287       296    +9     

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[Stranger6667]

Thanks!