docs: Bring myst_nb

myst_nb parser allows to parse cell tags. Currently we use an unreleased version.
Clone from https://github.com/executablebooks/MyST-NB and pip install -e . into the enviroment of the documentation generation.
See also executablebooks/MyST-NB#543

pyproject.toml

@@ -73,15 +73,16 @@ doc = [
     "ipyvtklink==0.2.3",
     "jupyter_sphinx==0.4.0",
     "jupytext==1.15.2",
-    "myst-parser==2.0.0",
+    "myst-parser==0.18",
+    "myst-nb==0.17.1",
     "nbconvert==7.9.2",
     "nbsphinx==0.9.3",
     "notebook==7.0.4",
     "numpydoc==1.6.0",
     "panel==1.2.3",
     "pyvista[trame]==0.41.1",
     "requests==2.31.0",
-    "sphinx==7.2.5",
+    "sphinx",
     "sphinx-autoapi==3.0.0", # "sphinx-autoapi @ git+https://github.com/jorgepiloto/sphinx-autoapi@feat/single-page-option", ---> Installed directly in workflow
     "sphinx-autodoc-typehints==1.24.0",
     "sphinx-copybutton==0.5.2",