add bokeh and matplotlib to the optional notebook requirements

Author: basnijholt

setup.py

@@ -59,6 +59,8 @@ def make_release_tree(self, base_dir, files):
         'jupyter_client>=5.2.2',  # because https://github.com/jupyter/jupyter_client/pull/314
         'holoviews>=1.9.1',
         'ipywidgets',
+        'bokeh',
+        'matplotlib',
     ],
 }