build(deps): bump protobufjs and @angular/fire in /firestore

Bumps [protobufjs](https://github.com/protobufjs/protobuf.js) to 7.6.0 and updates ancestor dependency [@angular/fire](https://github.com/angular/angularfire). These dependencies need to be updated together.


Updates `protobufjs` from 7.2.4 to 7.6.0
- [Release notes](https://github.com/protobufjs/protobuf.js/releases)
- [Changelog](https://github.com/protobufjs/protobuf.js/blob/protobufjs-v7.6.0/CHANGELOG.md)
- [Commits](protobufjs/protobuf.js@protobufjs-v7.2.4...protobufjs-v7.6.0)

Updates `@angular/fire` from 7.6.1 to 20.0.1
- [Release notes](https://github.com/angular/angularfire/releases)
- [Commits](angular/angularfire@7.6.1...20.0.1)

---
updated-dependencies:
- dependency-name: protobufjs
  dependency-version: 7.6.0
  dependency-type: indirect
- dependency-name: "@angular/fire"
  dependency-version: 20.0.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]