Bump mocha from 8.4.0 to 9.0.0 in /glean

Bumps [mocha](https://github.com/mochajs/mocha) from 8.4.0 to 9.0.0.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v8.4.0...v9.0.0)

---
updated-dependencies:
- dependency-name: mocha
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

glean/package-lock.json

@@ -93,7 +93,7 @@
     "jsdom-global": "3.0.2",
     "jsonschema": "^1.4.0",
     "madge": "^4.0.2",
-    "mocha": "^8.3.0",
+    "mocha": "^9.0.0",
     "npm-run-all": "^4.1.5",
     "selenium-webdriver": "^4.0.0-alpha.8",
     "sinon": "^11.0.0",