### Apache Airflow version

2.2.2 (latest released)

### Operating System

MacOS 11.6.1

### Versions of Apache Airflow Providers

$ pip freeze | grep airflow
apache-airflow==2.2.2
apache-airflow-providers-celery==2.1.0
apache-airflow-providers-ftp==2.0.1
apache-airflow-providers-http==2.0.1
apache-airflow-providers-imap==2.0.1
apache-airflow-providers-sqlite==2.0.1

### Deployment

Other

### Deployment details

`airflow standalone`

### What happened

```
AttributeError: 'NoneType' object has no attribute 'update_relative'
```

### What you expected to happen

Task group should be set as downstream of `start` task, and upstream of `end` task

### How to reproduce

* Add the following code to dags folder

```python
from datetime import datetime

from airflow.decorators import dag, task, task_group


@dag(start_date=datetime(2023, 1, 1), schedule_interval="@once")
def test_dag_1():
    @task
    def start():
        pass

    @task
    def do_thing(x):
        print(x)

    @task_group
    def do_all_things():
        do_thing(1)
        do_thing(2)

    @task
    def end():
        pass

    start() >> do_all_things() >> end()


test_dag_1()
```

* Run `airflow standalone`

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

tests/utils/test_task_group.py
execution_date = pendulum.parse("20200101")
    with DAG("test_build_task_group_context_manager", start_date=execution_date) as dag:
        task1 = DummyOperator(task_id="task1")
        with TaskGroup("group234") as group234:
            _ = DummyOperator(task_id="task2")
            with TaskGroup("group34") as group34:
                _ = DummyOperator(task_id="task3")
                _ = DummyOperator(task_id="task4")
        task5 = DummyOperator(task_id="task5")
        task1 >> group234
        group34 >> task5
    assert task1.get_direct_relative_ids(upstream=False) == {
        'group234.group34.task4',
        'group234.group34.task3',
        'group234.task2',
    }
    assert task5.get_direct_relative_ids(upstream=True) == {
        'group234.group34.task4',
        'group234.group34.task3',
    }
    assert dag.task_group.group_id is None
    assert dag.task_group.is_root
    assert set(dag.task_group.children.keys()) == {"task1", "group234", "task5"}
    assert group34.group_id == "group234.group34"
    assert task_group_to_dict(dag.task_group) == EXPECTED_JSON
def test_build_task_group():