I changed log_mass to mass, so stacking weights are a little bit more distributed, still not happy with this example. Fine for the moment because this PR updates the mechanics of how to get weighted predictions with the new versions of PyMC and ArviZ. But in a future PR I would like to update the example to show a better contrast between averaging models and picking "the best" one.

• Notebook follows style guide https://docs.pymc.io/en/latest/contributing/jupyter_style.html
• PR description contains a link to the relevant issue:
  • a tracker one for existing notebooks (tracker issues have the "tracker id" label)
  • or a proposal one for new notebooks
• Check the notebook is not excluded from any pre-commit check: https://github.com/pymc-devs/pymc-examples/blob/main/.pre-commit-config.yaml

Helpful links

• https://github.com/pymc-devs/pymc-examples/blob/main/CONTRIBUTING.md

📚 Documentation preview 📚: https://pymc-examples--687.org.readthedocs.build/en/687/