Port NBs to v4

[twiecki]

There are quite a few NBs that still need porting here in ToDo or Best Practices (v3): https://github.com/pymc-devs/pymc-examples/projects/1#card-75796525

How?

Run the scripts/rerun.py script (https://github.com/pymc-devs/pymc-examples/blob/main/scripts/rerun.py) which attempts to auto-update the code and rerun the NB. If it runs without error (which should be the default) it will commit the updated NB to a branch you specified. If not, you need to fix the NB manually, rerun it, and commit yourself.

After, create a PR to this repo.

Here are the docs from the rerun.py script:

This script/module may be used to re-run, commit & push notebooks
from the CLI or from another Python script (via import rerun).
Run python rerun.py -h to show the CLI help.
The example below does the following:

1. Re-runs the BEST notebook
2. Commits changes to a branch "rerun-best"
3. Push that branch to a remote named "mine"
   Assuming you did something like: git add remote mine https://github.com/yourgithubusername/pymc-examples

python scripts/rerun.py --fp_notebook=examples/case_studies/BEST.ipynb --commit_to=rerun-best --push_to=mine