Fix bug in implicit_size_from_params

[ricardoV94]

Also avoids some deprecation warnings in a separate commit

---

📚 Documentation preview 📚: https://pymc--7564.org.readthedocs.build/en/7564/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.83%. Comparing base (3057351) to head (d2215d4).
Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7564   +/-   ##
=======================================
  Coverage   92.83%   92.83%           
=======================================
  Files         106      106           
  Lines       17669    17669           
=======================================
  Hits        16403    16403           
  Misses       1266     1266           

Files with missing lines	Coverage Δ
pymc/distributions/continuous.py	98.25% <ø> (ø)
pymc/distributions/moments/means.py	100.00% <100.00%> (ø)
pymc/distributions/shape_utils.py	90.90% <100.00%> (ø)

... and 1 file with indirect coverage changes

[lucianopaz]

LGTM