chore(deps-dev): update mocha requirement from 5.2.0 to 6.1.4

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@v5.2.0...v6.1.4)

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

package.json

@@ -24,7 +24,7 @@
   },
   "devDependencies": {
     "chai": "4.2.0",
-    "mocha": "5.2.0",
+    "mocha": "6.1.4",
     "dotenv": "^6.1.0",
     "codecov": "3.5.0",
     "conventional-changelog-metahub": "2.0.2",