Add other mkdocs dependencies (for CI)

.github/workflows/docs-deploy.yml

@@ -27,6 +27,6 @@ jobs:
             mkdocs-material-
       - run: pip install mkdocs
       - run: pip install mkdocs-material
-      - run: pip install mkdocstrings
+      - run: pip install mkdocstrings[python]
       - run: pip install mknotebooks
       - run: mkdocs gh-deploy --force