chore(deps): bump protobufjs, @google-cloud/monitoring and firebase-admin

Bumps [protobufjs](https://github.com/protobufjs/protobuf.js) to 7.2.6 and updates ancestor dependencies [protobufjs](https://github.com/protobufjs/protobuf.js), [@google-cloud/monitoring](https://github.com/googleapis/google-cloud-node/tree/HEAD/packages/google-cloud-monitoring) and [firebase-admin](https://github.com/firebase/firebase-admin-node). These dependencies need to be updated together.

Updates `protobufjs` from 7.2.4 to 7.2.6
- [Release notes](https://github.com/protobufjs/protobuf.js/releases)
- [Changelog](https://github.com/protobufjs/protobuf.js/blob/master/CHANGELOG.md)
- [Commits](protobufjs/protobuf.js@protobufjs-v7.2.4...protobufjs-v7.2.6)

Updates `@google-cloud/monitoring` from 3.0.5 to 4.0.0
- [Release notes](https://github.com/googleapis/google-cloud-node/releases)
- [Changelog](https://github.com/googleapis/google-cloud-node/blob/main/packages/google-cloud-monitoring/CHANGELOG.md)
- [Commits](https://github.com/googleapis/google-cloud-node/commits/dns-v4.0.0/packages/google-cloud-monitoring)

Updates `firebase-admin` from 11.4.1 to 12.0.0
- [Release notes](https://github.com/firebase/firebase-admin-node/releases)
- [Commits](firebase/firebase-admin-node@v11.4.1...v12.0.0)

---
updated-dependencies:
- dependency-name: protobufjs
  dependency-type: indirect
- dependency-name: "@google-cloud/monitoring"
  dependency-type: direct:production
- dependency-name: firebase-admin
  dependency-type: direct:production
...

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

Author: dependabot[bot]