Test fails for the samples of golang.

### What happened?

```
cd a2a-samples/samples/go
go test ./...
```

```
--- FAIL: TestSendTaskStreaming (0.00s)
client_test.go:235: expected method message/send, got message/stream
FAIL
FAIL a2a/client 0.020s
? a2a/models [no test files]
ok a2a/server (cached)
FAIL
```

### Relevant log output

```shell

```

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct