Update dependency xml2js to v0.4.21

Author: renovate-bot

package.json

@@ -57,6 +57,6 @@
     "axios": "0.19.0",
     "jsonwebtoken": "8.5.1",
     "uuid-random": "1.0.9",
-    "xml2js": "0.4.19"
+    "xml2js": "0.4.21"
   }
 }