Update protobuf requirement in /client/python

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@v3.20.0...v5.27.0)

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

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

client/python/pyproject.toml

@@ -4,7 +4,7 @@ version = "0.3.3"
 description = "Armada gRPC API python client"
 readme = "README.md"
 requires-python = ">=3.7"
-dependencies = ["grpcio==1.58.0", "grpcio-tools==1.58.0", "mypy-protobuf>=3.2.0", "protobuf>=3.20,<5.0" ]
+dependencies = ["grpcio==1.58.0", "grpcio-tools==1.58.0", "mypy-protobuf>=3.2.0", "protobuf>=3.20,<6.0" ]
 license = { text = "Apache Software License" }
 authors = [{ name = "G-Research Open Source Software", email = "armada@armadaproject.io" }]