5.0: Update django.db.models.expressions

[JaeHyuckSa]

I have made things!

Update stubs for django.db.models.expressions for Django 5.0.

• django.db.models.expressions
  • django.db.models.expressions.BaseExpression.allowed_default was added
  • django.db.models.expressions.DatabaseDefault was added
  • django.db.models.expressions.Subquery.subquery was added

Related issues

Refs

• Django 5.0 Tracking Issue #1493

Upstream PR
django.db.models.expressions.Subquery.subquery

• Fixed #34551 -- Fixed a crash on combined aggregation over a subquery. django/django#16879

django.db.models.expressions.BaseExpression.allowed_default
django.db.models.expressions.DatabaseDefault

• Fixed #470 -- Added support for database defaults on fields. django/django#16092