### 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
"""TaskGroup for grouping related Tasks"""
        return task_3(task_2(task_1(value)))
    execution_date = pendulum.parse("20201109")
    with DAG(dag_id="example_task_group_decorator_mix", start_date=execution_date, tags=["example"]) as dag:
        t_start = PythonOperator(task_id='task_start', python_callable=task_start, dag=dag)
        with TaskGroup("section_1", tooltip="section_1") as section_1:
            sec_2 = section_2(t_start.output)
            task_s1 = DummyOperator(task_id="task_1")
            task_s2 = BashOperator(task_id="task_2", bash_command='echo 1')
            task_s3 = DummyOperator(task_id="task_3")
            sec_2.set_downstream(task_s1)
            task_s1 >> [task_s2, task_s3]
        t_end = PythonOperator(task_id='task_end', python_callable=task_end, dag=dag)
        t_start >> section_1 >> t_end
    node_ids = {
        'id': None,
        'children': [
            {
                'id': 'section_1',
                'children': [
                    {
                        'id': 'section_1.section_2',
                        'children': [
                            {'id': 'section_1.section_2.task_1'},
                            {'id': 'section_1.section_2.task_2'},
                            {'id': 'section_1.section_2.task_3'},
                        ],
                    },