fix(package): update express-winston to version 3.1.0

Closes #2

Author: greenkeeper[bot]

package.json

@@ -17,7 +17,7 @@
   },
   "homepage": "https://github.com/StageCloud/node-request-logger#readme",
   "dependencies": {
-    "express-winston": "^2.0.0",
+    "express-winston": "^3.1.0",
     "winston": "^2.2.0"
   }
 }