### Apache Airflow version

2.2.1 (latest released)

### Operating System

debian

### Versions of Apache Airflow Providers

apache-airflow==2.2.1
apache-airflow-providers-amazon==2.3.0
apache-airflow-providers-ftp==2.0.1
apache-airflow-providers-google==6.0.0
apache-airflow-providers-http==2.0.1
apache-airflow-providers-imap==2.0.1
apache-airflow-providers-jira==2.0.1
apache-airflow-providers-mysql==2.1.1
apache-airflow-providers-postgres==2.3.0
apache-airflow-providers-redis==2.0.1
apache-airflow-providers-sqlite==2.0.1
apache-airflow-providers-ssh==2.2.0

### Deployment

Other Docker-based deployment

### Deployment details

Dask executor, custom-built Docker images, postgres 12.7 backend

### What happened

I upgraded Airflow from 2.0.2 to 2.2.1, and some DAGs I have that used dateutils.relativedelta objects as schedule intervals stopped running

### What you expected to happen

The [code](https://github.com/apache/airflow/blob/2.2.1/airflow/models/dag.py#L101) for the schedule_interval parameter of the DAG constructor indicates that a relativedelta object is allowed, so I expected the DAG to be correctly parsed and scheduled.

### How to reproduce

Create a DAG that has a relativedelta object as its schedule interval, and it will not appear in the UI or be scheduled.

### Anything else

Here is the code that causes the failure within the PR where it was introduced: [link](https://github.com/apache/airflow/pull/17414/files#diff-ed37fe966e8247e0bfd8aa28bc2698febeec3807df5f5a00545ca80744f8aff6R267)

Here are the logs for the exception, found in the scheduler logs for the file that contains the offending DAG
<details><pre>
ERROR   | {dagbag.py:528} - 'relativedelta' object has no attribute 'total_seconds'
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/airflow/models/dagbag.py", line 515, in collect_dags
    found_dags = self.process_file(filepath, only_if_updated=only_if_updated, safe_mode=safe_mode)
  File "/usr/local/lib/python3.9/site-packages/airflow/models/dagbag.py", line 298, in process_file
    found_dags = self._process_modules(filepath, mods, file_last_changed_on_disk)
  File "/usr/local/lib/python3.9/site-packages/airflow/models/dagbag.py", line 401, in _process_modules
    dag.timetable.validate()
  File "/usr/local/lib/python3.9/site-packages/airflow/timetables/interval.py", line 274, in validate
    if self._delta.total_seconds() <= 0:
AttributeError: 'relativedelta' object has no attribute 'total_seconds'
</pre></details>

### 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)

airflow/timetables/interval.py
"""Figures out if the schedule has a fixed time (e.g. 3 AM every day).
    :return: True if the schedule has a fixed time, False if not.
    Detection is done by "peeking" the next two cron trigger time; if the
    two times have the same minute and hour value, the schedule is fixed,
    and we *don't* need to perform the DST fix.
    This assumes DST happens on whole minute changes (e.g. 12:59 -> 12:00).
    """
    cron = croniter(expression)
    next_a = cron.get_next(datetime.datetime)
    next_b = cron.get_next(datetime.datetime)
    return next_b.minute == next_a.minute and next_b.hour == next_a.hour
class CronDataIntervalTimetable(_DataIntervalTimetable):