Bump flat and mocha in /js

Bumps [flat](https://github.com/hughsk/flat) to 5.0.2 and updates ancestor dependency [mocha](https://github.com/mochajs/mocha). These dependencies need to be updated together.


Updates `flat` from 4.1.1 to 5.0.2
- [Release notes](https://github.com/hughsk/flat/releases)
- [Commits](https://github.com/hughsk/flat/compare/4.1.1...5.0.2)

Updates `mocha` from 7.2.0 to 10.2.0
- [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/v7.2.0...v10.2.0)

---
updated-dependencies:
- dependency-name: flat
  dependency-type: indirect
- dependency-name: mocha
  dependency-type: direct:development
...

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

js/package.json

@@ -34,6 +34,6 @@
     "selenium-webdriver": "3.6.0"
   },
   "devDependencies": {
-    "mocha": "^7.1.2"
+    "mocha": "^10.2.0"
   }
 }