Ensure that this works:

```python
@setup
def mytask():
    print("I am a setup task")

with dag_maker() as dag:
    mytask.override(task_id='newtask')

assert len(dag.task_group.children) == 1
setup_task = dag.task_group.children["newtask"]
assert setup_task._is_setup
```
and teardown also works
validate_group_key(group_id)
            else:
                if not isinstance(group_id, str):
                    raise ValueError("group_id must be str")
                if not group_id:
                    raise ValueError("group_id must not be empty")
            if not parent_group and not dag:
                raise AirflowException("TaskGroup can only be used inside a dag")
            parent_group = parent_group or TaskGroupContext.get_current_task_group(dag)
            if not parent_group:
                raise AirflowException("TaskGroup must have a parent_group except for the root TaskGroup")
            if dag is not parent_group.dag:
                raise RuntimeError(
                    "Cannot mix TaskGroups from different DAGs: %s and %s", dag, parent_group.dag
                )
            self.used_group_ids = parent_group.used_group_ids
        
        
        self._group_id = group_id
        self._check_for_group_id_collisions(add_suffix_on_collision)
        self.children: dict[str, DAGNode] = {}
        if parent_group:
            parent_group.add(self)
        self.used_group_ids.add(self.group_id)
        if self.group_id:
            self.used_group_ids.add(self.downstream_join_id)
            self.used_group_ids.add(self.upstream_join_id)
        self.tooltip = tooltip
        self.ui_color = ui_color