fix(package): update mocha to version 6.1.3

Closes #100

Author: greenkeeper[bot]

package.json

@@ -13,7 +13,7 @@
     "express": "4.16.4",
     "express-session": "1.15.6",
     "firebase-admin": "6.5.0",
-    "mocha": "6.0.0",
+    "mocha": "6.1.3",
     "moesif-express": "2.7.1",
     "mysql": "2.16.0",
     "node-telegram-bot-api": "0.30.0",