chore(package): update mocha to version 6.1.0

Closes #7

Author: greenkeeper[bot]

package.json

@@ -22,7 +22,7 @@
     "@babel/register": "^7.0.0",
     "axios": "^0.18.0",
     "chai": "^4.2.0",
-    "mocha": "^5.2.0",
+    "mocha": "^6.1.0",
     "nodemon": "^1.18.7",
     "morgan": "^1.9.1"
   },