chore: Bump Express PREP

This fixes "undefined" notifications being emitted when the requested notification format is not Solid PREP RDF.

Author: CxRes

package-lock.json

@@ -77,7 +77,7 @@
     "express-accept-events": "^0.3.0",
     "express-handlebars": "^5.3.5",
     "express-negotiate-events": "^0.3.0",
-    "express-prep": "^0.6.1",
+    "express-prep": "^0.6.2",
     "express-session": "^1.18.0",
     "extend": "^3.0.2",
     "from2": "^2.3.0",