chore(package): update mocha to version 4.1.0

Closes #8

Author: greenkeeper[bot]

package.json

@@ -4,7 +4,7 @@
   "description": "Typescript Typings for protobufjs",
   "devDependencies": {
     "chai": "^3.5.0",
-    "mocha": "^3.3.0",
+    "mocha": "^4.1.0",
     "source-map-support": "^0.4.0",
     "tslint": "^5.2.0",
     "typescript": "^2.3.2",