DOC Fix plotly rendering inside JupyterLite (scikit-learn#31400)

Author: lesteve

doc/conf.py

@@ -668,7 +668,7 @@ def notebook_modification_function(notebook_content, notebook_filename):
     if "seaborn" in notebook_content_str:
         code_lines.append("%pip install seaborn")
     if "plotly.express" in notebook_content_str:
-        code_lines.append("%pip install plotly")
+        code_lines.append("%pip install plotly nbformat")
     if "skimage" in notebook_content_str:
         code_lines.append("%pip install scikit-image")
     if "polars" in notebook_content_str: