chore(pkg): use rdflib >= 0.6.1 to keep compatibility with setuptools 58

--HG--
branch : 3.31

setup.py

@@ -75,7 +75,7 @@ setup(
         'markdown-urlize',
         'filelock',
         'rdflib >= 5.0.0, < 6.0.0',
-        'rdflib-jsonld',
+        'rdflib-jsonld >= 0.6.1',
         'pyramid >= 1.5.0, < 2.0.0',
         'waitress >= 1.4.0, < 2.0.0',
         'wsgicors >= 0.3',