Add typing to discrete distributions

[jessica-writes-code]

What is this PR about?
Per #5358 , it would be nice to have type hints for distribution parameters.

Checklist

• Explain important implementation details 👆
• Make sure that the pre-commit linting/style checks pass.
• Link relevant issues (preferably in nice commit messages)
• Are the changes covered by tests and docstrings?
• Fill out the short summary sections 👇

Major / Breaking Changes

• N/A

New features

• N/A

Bugfixes

• N/A

Documentation

• N/A

Maintenance

• Add typing for distribution parameters.

[canyon289]

Thanks for contributing to PyMC!

[codecov]

Codecov Report

Merging #6410 (03365b8) into main (1ed4475) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6410      +/-   ##
==========================================
- Coverage   91.99%   91.97%   -0.02%     
==========================================
  Files          94       94              
  Lines       15944    15945       +1     
==========================================
- Hits        14667    14665       -2     
- Misses       1277     1280       +3     

Impacted Files	Coverage Δ
pymc/distributions/discrete.py	98.73% <100.00%> (+<0.01%)	⬆️

... and 1 file with indirect coverage changes

[jessica-writes-code]

It seems like the new typing has introduced a mypy error that didn't exist before in discrete.py, but exists in several other files -- that the signatures for dist in the child classes are incompatible with the parent. I'm not sure there exists a good short-term fix, but I think there are two (probably more) potential long-term fixes:
(1) Adjust signature of dist in the Distribution class. (This will probably require adjusting how it is called in several places.)
(2) Rename the dist method of the Distribution class.
My vote is for (1), but I'm happy to work on either, if it would be useful.

(Also, apologies for not commenting on #5358 before starting this. I'll make sure to do that more effectively going forward.)

[ricardoV94]

Has this PR been superseded by others?

Not sure who to ping: @OriolAbril ?

[OriolAbril]

I have no idea about typing, sorry

[ricardoV94]

Sorry, I thought this PR was part of some sprint

[ricardoV94]

It seems the type-hints are still missing on main. @jessica-writes-code can you fix the conflicts that have emerged in the PR?

[jessica-writes-code]

@ricardoV94 Changes made!

[ricardoV94]

Looks good to me. Thanks @jessica-writes-code

[jessica-writes-code]

@ricardoV94 Mypy check is failing. See my comment from Dec 25. Happy to pursue either option or any alternative you suggest!

[ricardoV94]

I am closing this one as a long time has passed. Type hints may already have been improved in the meantime. Feel free to reopen a PR if type hints are still missing. Thanks for the help!