Draft: add script to migrate data to py3
follow !2145 (comment 243116)
one approach to convert all object might be to have an external script reading all records from the ZODB and if the pickle data has some python2
STRING, load and save again the object for thisoid. Once this external script does not find anySTRING, it means we no longer needzodbupdate. I guess this could be a way, we can try this.