chore(package): update mocha to version 6.0.1

Closes #131

Author: greenkeeper[bot]

package.json

@@ -44,7 +44,7 @@
     "chai": "^4.1.2",
     "chance": "^1.0.18",
     "coveralls": "^3.0.2",
-    "mocha": "^5.2.0",
+    "mocha": "^6.0.1",
     "nyc": "^13.1.0",
     "request-promise-native": "^1.0.5",
     "rimraf": "^2.6.2",