Update express-rate-limit to version 5.5.1

Author: depfu[bot]

package-lock.json

@@ -14,7 +14,7 @@
     "cors": "^2.8.5",
     "debug": "~2.6.9",
     "express": "~4.16.1",
-    "express-rate-limit": "^5.2.3",
+    "express-rate-limit": "^5.5.1",
     "helmet": "^4.3.1",
     "hpp": "^0.2.3",
     "http-errors": "~1.6.3",