python3Packages.cirq-google: fix build (#355905)

pkgs/development/python-modules/cirq-google/default.nix

···
   protobuf,
   pytestCheckHook,
   setuptools,
+  protobuf4,
+  fetchpatch,
 }:
 
 buildPythonPackage rec {
···
   sourceRoot = "${src.name}/${pname}";
 
   build-system = [ setuptools ];
+
+  patches = [
+    # https://github.com/quantumlib/Cirq/pull/6683 Support for protobuf5
+    (fetchpatch {
+      url = "https://github.com/quantumlib/Cirq/commit/bae02e4d83aafa29f50aa52073d86eb913ccb2d3.patch";
+      hash = "sha256-MqHhKa38BTM6viQtWik0TQjN0OPdrwzCZkkqZsiyF5w=";
+      includes = [ "cirq_google/serialization/arg_func_langs_test.py" ];
+      stripLen = 1;
+    })
+  ];
+
+  pythonRelaxDeps = [
+    "protobuf"
+  ];
 
   dependencies = [
     cirq-core