Update dependency rdf-string to v2

Author: renovate[bot]

package.json

@@ -73,7 +73,7 @@
     "leaflet": "^1.7.1",
     "minimist": "^1.2.5",
     "n3": "^1.16.2",
-    "rdf-string": "^1.6.1",
+    "rdf-string": "^2.0.0",
     "relative-to-absolute-iri": "^1.0.6",
     "sparqljs": "^3.7.3",
     "string-replace-loader": "^3.1.0",