chore(package): update mocha to version 6.0.2

Closes #24

Author: greenkeeper[bot]

package.json

@@ -54,7 +54,7 @@
     "coveralls": "^3.0.1",
     "eslint": "^4.19.1",
     "istanbul": "^0.4.5",
-    "mocha": "^5.2.0",
+    "mocha": "^6.0.2",
     "mocha-lcov-reporter": "^1.3.0",
     "prettier-eslint": "^8.8.1"
   }