build(deps): bump protobuf from 5.1.0 to 6.0.0 (#168)

Bumps [protobuf](https://github.com/google/protobuf.dart) from 5.1.0 to 6.0.0.
- [Release notes](https://github.com/google/protobuf.dart/releases)
- [Commits](https://github.com/google/protobuf.dart/compare/protobuf-v5.1.0...protobuf-v6.0.0)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pubspec.yaml

@@ -72,7 +72,7 @@ dependencies:
 
   # gRPC and protobuf
   grpc: ^5.0.0
-  protobuf: ^5.1.0
+  protobuf: ^6.0.0
 dependency_overrides:
   http: ^1.6.0
   intl: ^0.20.2