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
from airflow.decorators import task
    from airflow.models.xcom_arg import XComArg
    from airflow.serialization.serialized_objects import _ExpandInputRef, _XComRef
    with DAG("test-dag", start_date=datetime(2020, 1, 1)) as dag:
        op1 = BaseOperator(task_id="op1")
        @task(retry_delay=30)
        def x(arg1, arg2, arg3):
            print(arg1, arg2, arg3)
        x.partial(arg1=[1, 2, {"a": "b"}]).expand_kwargs(XComArg(op1), strict=strict)
    original = dag.get_task("x")
    serialized = SerializedBaseOperator.serialize(original)
    assert serialized == {
        "_is_empty": False,
        "_is_mapped": True,
        "_task_module": "airflow.decorators.python",
        "_task_type": "_PythonDecoratedOperator",
        "_operator_name": "@task",
        "downstream_task_ids": [],
        "partial_kwargs": {
            "op_args": [],
            "op_kwargs": {
                "__type": "dict",
                "__var": {"arg1": [1, 2, {"__type": "dict", "__var": {"a": "b"}}]},