fix(deps): update dependency protobuf to v6

Author: renovate[bot]

pyproject.toml

@@ -26,7 +26,7 @@ python = "^3.9"
 anyio = "^4.6.0"
 grpcio = "^1.66"
 grpcio-health-checking = "^1.66"
-protobuf = "^5.28"
+protobuf = "^6.0.0"
 oauthlib = "^3.1.0"
 requests-oauthlib = ">=1.3.0,<3.0.0"
 typing-extensions = "^4.11.0"