Exception calling application: No positional arguments allowed with google.protobuf.Empty

## Bug Report

### Version

[dependencies]
tonic = "0.9.2"
tokio = { version = "1.28.0", features = ["macros", "rt-multi-thread"] }
prost = "0.11.9"
prost-types = "0.11.9"

[build-dependencies]
tonic-build = "0.9.2"

### Platform

archlinux 64 latest

### Description

I have this in my .proto:

```
service GoodService {
rpc NiceRequest (google.protobuf.Empty) returns (GoodResponse) {}
}
```

In Rust:
```
client.nice_request(()).await?;
```

The server is implemented in Python, code generated using latest grpcio.

The error after establishing connection and calling the function:

```
Error: Status { code: Unknown, message: "Exception calling application: No positional arguments allowed", metadata: MetadataMap { headers: {"content-type": "application/grpc"} }, source: None }
```