Bump mocha from 5.2.0 to 6.0.0

Bumps [mocha](https://github.com/mochajs/mocha) from 5.2.0 to 6.0.0.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v5.2.0...v6.0.0)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot-support

package.json

@@ -147,7 +147,7 @@
     "html-differ": "^1.4.0",
     "lodash.uniq": "^4.5.0",
     "mkdirp": "^0.5.1",
-    "mocha": "^5.2.0",
+    "mocha": "^6.0.0",
     "prettier": "1.16.4",
     "puppeteer": "^1.12.2",
     "qunit": "^2.9.1",