add rdflib

Author: bourgeoa

package-lock.json

@@ -103,6 +103,7 @@
     "nyc": "^15.1.0",
     "oidc-op-express": "^0.0.3",
     "owasp-password-strength-test": "^1.3.0",
+    "rdflib": "^2.3.0",
     "recursive-readdir": "^2.2.3",
     "rimraf": "^3.0.2",
     "solid-auth-client": "^2.5.6",