DatabaseScheduler ignores 'expires' option

[spoksss]

Fix: #393

[spoksss]

The same fix should work with django-celery==3.2

[spoksss]

Example how I use it, maybe will be helpful.

from celery import Task

class MyTask(Task):

    expires = 60 * 2
    ...

[Copilot]

Pull Request Overview

This PR addresses issue #393 by updating the DatabaseScheduler to correctly handle the "expires" option.

• Introduces a check for an "expires" value in the options.
• Deletes the model's DateTimeField attribute "expires" when necessary and reassigns it as a simple int.