Missing `constraint` field for constraint related migration operations

[SpyrosRoum]

Bug report

What's wrong

The AddConstraint and AlterConstraint migration operations should have a constraint field.

Example code:

    def foo(self, op: AddConstraint) -> Any:
        return op.constraint

Result of running mypy on it:
error: "AddConstraint" has no attribute "constraint" [attr-defined]

How is that should be

The constraint field should be added to these operations

System information

• OS: MacOS 15.7.1
• python version: 3.12.x
• django version: 5.2.x
• mypy version: 1.18.2
• django-stubs version: 5.2.7
• django-stubs-ext version: 5.2.7

[SpyrosRoum]

Assuming this is actually an omission from django-stubs and I'm not doing something wrong, I'm willing to open a PR to fix it :)