chore(package): update mocha to version 6.2.0

Closes #216

Author: greenkeeper[bot]

package.json

@@ -31,7 +31,7 @@
     "eslint-plugin-import": "^2.0.0",
     "eslint-plugin-jsx-a11y": "^5.1.1",
     "eslint-plugin-react": "^7.3.0",
-    "mocha": "^5.2.0",
+    "mocha": "^6.2.0",
     "nyc": "^14.0.0",
     "typescript": "^3.3.3333"
   },