chore(deps): update dependency mocha to v6

Author: renovate[bot]

package.json

@@ -45,7 +45,7 @@
     "eslint-plugin-react": "7.20.6",
     "expect": "1.20.2",
     "json": "9.0.6",
-    "mocha": "5.2.0",
+    "mocha": "6.2.3",
     "mversion": "1.13.0",
     "react": "16.13.1"
   },