Bump jsonwebtoken and firebase-admin in /backend

Bumps [jsonwebtoken](https://github.com/auth0/node-jsonwebtoken) to 9.0.0 and updates ancestor dependency [firebase-admin](https://github.com/firebase/firebase-admin-node). These dependencies need to be updated together.


Updates `jsonwebtoken` from 8.5.1 to 9.0.0
- [Release notes](https://github.com/auth0/node-jsonwebtoken/releases)
- [Changelog](https://github.com/auth0/node-jsonwebtoken/blob/master/CHANGELOG.md)
- [Commits](auth0/node-jsonwebtoken@v8.5.1...v9.0.0)

Updates `firebase-admin` from 8.13.0 to 11.4.1
- [Release notes](https://github.com/firebase/firebase-admin-node/releases)
- [Commits](firebase/firebase-admin-node@v8.13.0...v11.4.1)

---
updated-dependencies:
- dependency-name: jsonwebtoken
  dependency-type: indirect
- dependency-name: firebase-admin
  dependency-type: direct:production
...

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