[Bug]: Wrong error when sending a message for a terminal task

### What happened?

What the spec says about the "Send Message" operation errors:
> UnsupportedOperationError: Messages sent to Tasks that are in a terminal state [...]

What the code does (`on_message_send(...)->_setup_message_execution(...)`):
```python
if task.status.state in TERMINAL_TASK_STATES:
raise InvalidParamsError(
message=f'Task {task.id} is in terminal state: {task.status.state}'
)
```

### Relevant log output

```shell

```

### Code of Conduct

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