update to v4 and address comments

Author: OriolAbril

.pre-commit-config.yaml

@@ -1,16 +1,16 @@
 repos:
 - repo: https://github.com/mwouts/jupytext
-  rev: v1.13.7
+  rev: v1.14.1
   hooks:
   - id: jupytext
     files: ^examples/.+\.ipynb$
     args: ["--sync"]
 - repo: https://github.com/psf/black
-  rev: 22.3.0
+  rev: 22.10.0
   hooks:
     - id: black-jupyter
 - repo: https://github.com/nbQA-dev/nbQA
-  rev: 1.1.0
+  rev: 1.5.3
   hooks:
     - id: nbqa-isort
       additional_dependencies: [isort==5.6.4]
@@ -106,13 +106,13 @@ repos:
       language: pygrep
       types_or: [markdown, rst, jupyter]
 - repo: https://github.com/mwouts/jupytext
-  rev: v1.13.7
+  rev: v1.14.1
   hooks:
   - id: jupytext
     files: ^examples/.+\.ipynb$
     args: ["--sync"]
 - repo: https://github.com/codespell-project/codespell
-  rev: v2.1.0
+  rev: v2.2.2
   hooks:
   - id: codespell
     files: myst_nbs/

examples/gaussian_processes/GP-MeansAndCovs.ipynb

@@ -467,6 +467,15 @@ @misc{quiroga2022bart
   year          = {2022},
   copyright     = {Creative Commons Attribution Share Alike 4.0 International}
 }
+@unpublished{padonou2015polar,
+  title         = {{Polar Gaussian Processes for Predicting on Circular Domains}},
+  author        = {Padonou, Esp{\'e}ran and Roustant, O},
+  url           = {https://hal.archives-ouvertes.fr/hal-01119942},
+  note          = {working paper or preprint},
+  year          = {2015},
+  month         = Feb,
+  pdf           = {https://hal.archives-ouvertes.fr/hal-01119942v1/file/PolarGP\_CircularDomains.pdf}
+}
 @book{rasmussen2003gaussian,
   title         = {Gaussian Processes for Machine Learning},
   author        = {Rasmussen, Carl Edward and Williams, Christopher K. I.},