small fix

component/jupyter_renderjs/buildout.cfg

 [buildout]
 parts =
+  jupyter-pip
   renderjs_nbextension
 
 
+[jupyter-pip]
+recipe = zc.recipe.egg:custom
+egg = jupyter-pip
+
 # renderjs_nbextension installed from latest git version
 [renderjs_nbextension]
 recipe = zc.recipe.egg:develop
@@ -25,4 +30,4 @@ recipe = plone.recipe.command
 command = cd "${renderjs_nbextension-repository:location}" && /sbin/git submodule update --init
 stop-on-error = true
 # propagate location of main repo
-location= ${renderjs_nbextension-repository:location}
\ No newline at end of file
+location= ${renderjs_nbextension-repository:location}