Implement ChiSquare via Gamma

[wd60622]

Motivation for these changes

Simplify by using the gamma distribution directly based on PyMC PR

Implementation details

Remove any ChiSquare reference including the rewrites and documentation

Checklist

• Explain motivation and implementation 👆
• Make sure that the pre-commit linting/style checks pass.
• Link relevant issues, preferably in nice commit messages.
• The commits correspond to relevant logical changes. Note that if they don't, we will rewrite/rebase/squash the git history before merging.
• Are the changes covered by tests and docstrings?
• Fill out the short summary sections 👇

Major / Breaking Changes

• ChiSquareRV doesn't exist

New features

• ...

Bugfixes

• ...

Documentation

• Removal of ChiSquareRV

Maintenance

• ...

[codecov-commenter]

Codecov Report

Merging #490 (b720605) into main (0f802ab) will increase coverage by 0.00%.
Report is 2 commits behind head on main.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #490   +/-   ##
=======================================
  Coverage   80.76%   80.76%           
=======================================
  Files         161      161           
  Lines       46080    46070   -10     
  Branches    11258    11256    -2     
=======================================
- Hits        37218    37210    -8     
+ Misses       6635     6634    -1     
+ Partials     2227     2226    -1     

Files	Coverage Δ
pytensor/link/numba/dispatch/random.py	98.83% <ø> (-0.01%)	⬇️
pytensor/tensor/random/basic.py	99.04% <100.00%> (-0.02%)	⬇️
pytensor/tensor/random/rewriting/jax.py	100.00% <ø> (ø)

... and 2 files with indirect coverage changes

[ricardoV94]

Thanks!

[wd60622]

Thanks!

Thanks for the feedback!