build: added missing myst-nb docs dependency

pyproject.toml

@@ -38,8 +38,7 @@ Repository = "https://github.com/martibosch/pylandstats"
 [project.optional-dependencies]
 test = ["coverage[toml]", "pytest", "pytest-cov", "ruff"]
 dev = ["build", "commitizen", "nox", "pre-commit", "pip", "toml", "twine"]
-doc = ["m2r2", "pydata-sphinx-theme", "sphinx"]
-
+doc = ["m2r2", "myst-nb", "pydata-sphinx-theme", "sphinx"]
 # [tool.setuptools]
 # ext-modules = [
 #     {name="adjacency", sources=["pylandstats/adjacency.pyx"]}