Bump micromatch and firebase-admin in /functions/testapp/functions

Removes [micromatch](https://github.com/micromatch/micromatch). It's no longer used after updating ancestor dependency [firebase-admin](https://github.com/firebase/firebase-admin-node). These dependencies need to be updated together.


Removes `micromatch`

Updates `firebase-admin` from 5.10.0 to 12.4.0
- [Release notes](https://github.com/firebase/firebase-admin-node/releases)
- [Commits](firebase/firebase-admin-node@v5.10.0...v12.4.0)

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

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

Author: dependabot[bot]