Port Prior class from PyMC-Marketing

[williambdean]

This ports the Prior class from PyMC-Marketing to pymc_extras.

The deserialize module is coming along for the ride as well.

Closes #448

CC: @drbenvincent

TODO:

• Get rid of any PyMC-Marketing references

[williambdean]

test_prior file isn't being run? At least what the action logs are showing

[drbenvincent]

First time playing around with pymc-extras. I did:

conda env create -f conda-envs/environment-test.yml
conda activate pymc-extras-test
pytest tests/test_prior.py

and I got

=============================================================== test session starts ===============================================================
platform darwin -- Python 3.12.10, pytest-8.3.5, pluggy-1.6.0 -- /Users/benjamv/miniforge3/envs/pymc-extras-test/bin/python3.12
cachedir: .pytest_cache
rootdir: /Users/benjamv/git/pymc-extras
configfile: pyproject.toml
plugins: cov-6.1.1
collected 0 items / 2 skipped                                                                                                                     

=============================================================== 2 skipped in 35.11s ===============================================================

I'm probably doing something wrong with the environment setup?