Bump mocha from 6.2.3 to 8.1.1 (#500)

Bumps [mocha](https://github.com/mochajs/mocha) from 6.2.3 to 8.1.1.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v6.2.3...v8.1.1)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

package.json

@@ -136,7 +136,7 @@
     "eslint-plugin-ember": "^8.9.1",
     "eslint-plugin-node": "^11.1.0",
     "loader.js": "^4.7.0",
-    "mocha": "^6.2.3",
+    "mocha": "^8.1.1",
     "npm-run-all": "^4.1.5",
     "qunit-dom": "^1.2.0",
     "release-it": "^13.5.7",