chore(package): update mocha to version 6.0.1

Closes #31

Author: greenkeeper[bot]

package.json

@@ -36,7 +36,7 @@
   "devDependencies": {
     "fs-extra": "^2.1.2",
     "jshint": "^2.8.0",
-    "mocha": "^3.2.0",
+    "mocha": "^6.0.1",
     "yeoman-test": "^1.6.0",
     "yeoman-assert": "3.1.0"
   }