Update pyproject.toml

[juanitorduz]

Remove pymc 5.23 upper bound from dependencies. We expect the latest release of https://github.com/pymc-devs/pytensor solved the issue.

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📚 Documentation preview 📚: https://pymc-marketing--1737.org.readthedocs.build/en/1737/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.59%. Comparing base (81503f5) to head (9f4a570).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1737   +/-   ##
=======================================
  Coverage   91.59%   91.59%           
=======================================
  Files          60       60           
  Lines        6782     6782           
=======================================
  Hits         6212     6212           
  Misses        570      570           

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