build(deps): bump firebase-admin from 11.0.0 to 13.7.0 in /functions

Bumps [firebase-admin](https://github.com/firebase/firebase-admin-node) from 11.0.0 to 13.7.0.
- [Release notes](https://github.com/firebase/firebase-admin-node/releases)
- [Changelog](https://github.com/firebase/firebase-admin-node/blob/main/CHANGELOG.md)
- [Commits](firebase/firebase-admin-node@v11.0.0...v13.7.0)

---
updated-dependencies:
- dependency-name: firebase-admin
  dependency-version: 13.7.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Author: dependabot[bot]