cubicweb-dataio #3723533 error when rdflib is not installed [validation pending]

importing the views.py raise NameError when rdflib is not installed

priorityimportant
typebug
done in0.5.0
load0.250
load left0.000
closed by#4ea3eb232a9f [views] fix NameError when rdflib is not available (closes #3723533)
patch[views] fix NameError when rdflib is not available (closes #3723533) [applied]