chore(package): update mocha to version 6.2.0

Closes #73

Author: greenkeeper[bot]

package.json

@@ -51,7 +51,7 @@
         "eslint": "~5.0.1",
         "eslint-plugin-react": "~7.10.0",
         "lint-staged": "^7.0.3",
-        "mocha": "^5.0.5",
+        "mocha": "^6.2.0",
         "prettier": "^1.11.1"
     },
     "peerDependencies": {