Add correct return type for assertTemplateNotUsed

Author: meshy

pytest_django/asserts.py

@@ -41,7 +41,7 @@ def assertion_func(*args, **kwargs):
 
 if TYPE_CHECKING:
     from django.http import HttpResponse
-    from django.test.testcases import _AssertTemplateUsedContext
+    from django.test.testcases import _AssertTemplateNotUsedContext, _AssertTemplateUsedContext
 
     def assertRedirects(
         response: HttpResponse,
@@ -110,7 +110,7 @@ def assertTemplateNotUsed(
         response: Optional[HttpResponse] = ...,
         template_name: Optional[str] = ...,
         msg_prefix: str = ...,
-    ) -> None:
+    ) -> _AssertTemplateNotUsedContext:
         ...
 
     def assertRaisesMessage(