
**Apache Airflow version**:

master

**What happened**:

https://github.com/apache/airflow/blob/master/airflow/models/baseoperator.py#L356 --> should be timedelta not datetime


tests/serialization/test_dag_serialization.py
def poke(self, context):
                return False
        op = DummySensor(task_id='dummy', mode=mode, poke_interval=23)
        blob = SerializedBaseOperator.serialize_operator(op)
        if expect_custom_deps:
            assert "deps" in blob
        else:
            assert "deps" not in blob
        serialized_op = SerializedBaseOperator.deserialize_operator(blob)
        assert op.deps == serialized_op.deps
    @parameterized.expand(
        [
            ({"on_success_callback": lambda x: print("hi")}, True),
            ({}, False),
        ]
    )
    def test_dag_on_success_callback_roundtrip(self, passed_success_callback, expected_value):