stack/erp5: Add dependencies for juptyer to html conversion

stack/erp5/buildout.cfg

@@ -563,6 +563,10 @@ eggs = ${neoppod:eggs}
 # Used by ERP5 Jupyter backend
   ipykernel
 
+# Used by Jupyter notebook to html conversion
+  nbconvert
+  nbformat
+
 # Used by DiffTool
   deepdiff
   unidiff
@@ -771,3 +775,7 @@ strict-rfc3339 = 0.7
 webcolors = 1.10
 rfc3987 = 1.3.8
 jsonpointer = 2.2
+
+# nbconvert 4.2.0 depends on entrypoints egg that is not available as tar/zip source.
+nbconvert = 4.1.0
+nbformat = 4.3.0

[Levin Zimmermann]

(This is only needed if one would like to use Juptyer toHtml method in an ERP5 instance without Wendelin. When using Wendelin the nbconvert and nbformat modules are provided by the ipython egg.)