Support for Django Manager/QuerySet

Are you planning to support Django's Manager/QuerySet interaction?

Example:

```python
from django.db import models

class NotificationQuerySet(models.QuerySet["Notification"]):
def resolved(self):
return self.filter(resolved_at__isnull=False)

class Notification(models.Model):
resolved_at = models.DateTimeField(null=True, blank=True)

objects = NotificationQuerySet.as_manager()

Notification.objects.resolved()
# => Object of class `Manager` has no attribute `resolved`

Notification.objects.all().resolved()
# .all() resolves to QuerySet[Notification, Notification]
# => Object of class `QuerySet` has no attribute `resolved`
```

I would expect both of these to work. Similarly for related managers, e.g. `user.notification_set.resolved()`.

Apologies if there's already an issue about this, I've looked and couldn't find one.