Update protobuf requirement from <5,>=4.25.3 to >=4.25.3,<6

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@v4.25.3...v5.27.0)

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

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

Author: dependabot[bot]

pyproject.toml

@@ -32,7 +32,7 @@ dependencies = [
   "frequenz-client-common >= 0.2.0, < 0.3",
   "grpcio >= 1.54.2, < 2",
   "grpcio-tools >= 1.54.2, < 2",
-  "protobuf >= 4.25.3, < 5",
+  "protobuf >= 4.25.3, < 6",
 ]
 dynamic = ["version"]