Step 5 explicitly avoids RDFExporter's compact projection and builds
the Turtle export from the TripletStore's own triples instead, but the
Summary cell still credited RDFExporter -- a leftover from before the
rdflib-based export replaced it. Correct the claim to match the code.
Also pin the install to >=0.6.7: earlier releases could return
ontology classes with an empty uri (#1103), which made entity_type
mappings silently resolve to None instead of raising, so the notebook
would appear to pass while never actually typing its instances.