chore(deps-dev): update mocha requirement from ^5.0.0 to ^6.2.0

Updates the requirements on [mocha](https://github.com/mochajs/mocha) to permit the latest version.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v5.0.0...v6.2.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -142,7 +142,7 @@
   },
   "devDependencies": {
     "github-changes": "^1.1.2",
-    "mocha": "^5.0.0",
+    "mocha": "^6.2.0",
     "nodeunit": "^0.11.2",
     "npm-release": "^1.0.0",
     "npm-run-all": "^4.1.3",