How to generate async/await version with gRPC Swift?

Question

We are currently generating swift code with gRPC.

protoc <proto_path> --grpc-swift_opt=Client=true,Server=false 
                    --grpc-swift_out=. 
                    --swift_opt=Visibility=Public

We are looking to migrate to async-await. Any idea, what argument we have to pass to generate async-await version code?

Thank you in advance