Improve types for QuerySet.contains and bulk_create

[adamchainz]

I have made things!

Copying in review from #1131.

Related issues

n/a

[adamchainz]

using _T here gave me:

django-stubs/db/models/query.pyi:113: error: Cannot use a covariant type variable as a parameter
django-stubs/db/models/query.pyi:114: error: Cannot use a covariant type variable as a parameter

But looking at the source, it seems any instance of a model class is acceptable:

https://github.com/django/django/blob/b92ffebb0cdc469baaf1b8f0e72dddb069eb2fb4/django/db/models/query.py#L1241-L1255

hence change to models.Model

[sobolevn]

Wow, update_conflicts=True looks like an amazing feature!

[adamchainz]

Yeah!

I suppose for strict accuracy, we could use @overload to enforce that ignore_conflicts and update_conflicts are not passed at the same time, and that the fields are passed if update_conflicts is True, etc. But I cba to enumerate all the cases right now 😅