chore(deps): bump firebase-functions from 4.2.1 to 6.2.0 in /functions

Bumps [firebase-functions](https://github.com/firebase/firebase-functions) from 4.2.1 to 6.2.0.
- [Release notes](https://github.com/firebase/firebase-functions/releases)
- [Changelog](https://github.com/firebase/firebase-functions/blob/master/tsconfig.release.json)
- [Commits](firebase/firebase-functions@v4.2.1...v6.2.0)

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

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