Update udata/rdf.py
Update udata/rdf.py

Co-authored-by: Alexandre Bulté <b30f4169e054ee7b8c243480bcfcef62416f3b08@bulte.net>
etalab/udata,opendatateam/udata,opendatateam/udata,etalab/udata,etalab/udata,opendatateam/udata