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
"""
    Used for testing custom dependency detector.
    TODO: remove in Airflow 3.0
    """
class CustomDependencyDetector(DependencyDetector):
    """
    Prior to deprecation of custom dependency detector, the return type as DagDependency | None.
    This class verifies that custom dependency detector classes which assume that return type will still
    work until support for them is removed in 3.0.
    TODO: remove in Airflow 3.0
    """
    @staticmethod
    def detect_task_dependencies(task: Operator) -> DagDependency | None:  
        if isinstance(task, CustomDepOperator):
            return DagDependency(
                source=task.dag_id,
                target="nothing",
                dependency_type="abc",
                dependency_id=task.task_id,
            )
        else:
            return DependencyDetector().detect_task_dependencies(task)