Update python to 3.13 and use it as the default for automated workflows

[margalva]

As requested by pyansys core team:

#194

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 61.89%. Comparing base (d415360) to head (662c842).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/ansys/dynamicreporting/core/serverless/item.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #195      +/-   ##
==========================================
- Coverage   62.45%   61.89%   -0.56%     
==========================================
  Files          22       22              
  Lines        6416     6475      +59     
  Branches     1213     1231      +18     
==========================================
+ Hits         4007     4008       +1     
- Misses       2035     2093      +58     
  Partials      374      374              

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