chore(deps): bump firebase-functions from 3.16.0 to 4.9.0 in /functions

Bumps [firebase-functions](https://github.com/firebase/firebase-functions) from 3.16.0 to 4.9.0.
- [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@v3.16.0...v4.9.0)

---
updated-dependencies:
- dependency-name: firebase-functions
  dependency-version: 4.9.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Author: dependabot[bot]