Update GP Marginal and Latent notebooks to v5

[fonnesbeck]

Description

Updates to GP notebooks based on API changes in V5. Notably, using sampling everywhere instead of find_MAP, since sample_posterior_predictive no longer works properly with MAP estimates.

• [x] Notebook follows style guide https://docs.pymc.io/en/latest/contributing/jupyter_style.html
• [x] 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
• [x] 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

[review-notebook-app[bot]]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[twiecki]

Ping @fonnesbeck

[fonnesbeck]

Hi!

[OriolAbril]

@fonnesbeck I think you'll need to delete the branch and create it again. I tried to rebase and I had merge issues from some 2022 commits still in this branch. I think I manage to fix the issues anyway and will merge if checks pass