chore(package): update mocha to version 6.0.1

Author: greenkeeper[bot]

package.json

@@ -27,7 +27,7 @@
     "coveralls": "^3.0.0",
     "eslint": "^4.15.0",
     "istanbul": "^0.4.5",
-    "mocha": "^5.0.0",
+    "mocha": "^6.0.1",
     "should": "^13.0.0"
   },
   "files": [