Update mocha requirement from ^5.2.0 to ^6.0.0

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](https://github.com/mochajs/mocha/compare/v5.2.0...v6.0.0)

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

package.json

@@ -47,7 +47,7 @@
     "glob": "^7.1.3",
     "inquirer": "^6.2.1",
     "lerna": "^3.4.3",
-    "mocha": "^5.2.0",
+    "mocha": "^6.0.0",
     "mocha-chrome": "^2.0.0",
     "node-sass": "^4.9.4",
     "rollup": "^1.1.0",