Bump @firebase/util and firebase-admin in /backend

Bumps [@firebase/util](https://github.com/firebase/firebase-js-sdk/tree/HEAD/packages/util) to 1.6.3 and updates ancestor dependency [firebase-admin](https://github.com/firebase/firebase-admin-node). These dependencies need to be updated together.


Updates `@firebase/util` from 0.3.2 to 1.6.3
- [Release notes](https://github.com/firebase/firebase-js-sdk/releases)
- [Changelog](https://github.com/firebase/firebase-js-sdk/blob/master/packages/util/CHANGELOG.md)
- [Commits](https://github.com/firebase/firebase-js-sdk/commits/@firebase/[email protected]/packages/util)

Updates `firebase-admin` from 8.13.0 to 11.0.1
- [Release notes](https://github.com/firebase/firebase-admin-node/releases)
- [Commits](firebase/firebase-admin-node@v8.13.0...v11.0.1)

---
updated-dependencies:
- dependency-name: "@firebase/util"
  dependency-type: indirect
- dependency-name: firebase-admin
  dependency-type: direct:production
...

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

Author: dependabot[bot]