Update dependency mocha to v6.2.0

Author: renovate-bot

package-lock.json

@@ -35,7 +35,7 @@
     "karma-sauce-launcher": "2.0.2",
     "karma-sourcemap-loader": "0.3.7",
     "lint-staged": "9.2.0",
-    "mocha": "6.1.4",
+    "mocha": "6.2.0",
     "npm-run-all": "4.1.5",
     "phantomjs-prebuilt": "2.1.16",
     "prettier": "1.18.2",