Update protobuf requirement from <6,>=5.29.3 to >=5.29.3,<7

Updates the requirements on [protobuf](https://github.com/protocolbuffers/protobuf) to permit the latest version.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](protocolbuffers/protobuf@v5.29.3...v6.30.2)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-version: 6.30.2
  dependency-type: direct:production
...

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

Author: dependabot[bot]

pyproject.toml

@@ -31,7 +31,7 @@ dependencies = [
   "frequenz-api-reporting >= 0.7.0, < 0.8",
   "frequenz-client-common >= 0.3.0, < 0.4",
   "grpcio >=1.70.0, < 2",
-  "protobuf >=5.29.3, < 6",
+  "protobuf >= 5.29.3, < 7",
   "frequenz-client-base >= 0.8.0, < 0.10.0",
 ]
 dynamic = ["version"]