Two small improvements (#217)

* Add return type for admin.SimpleListFilter.lookups

* force_login() can take any user, not just builtin

django-stubs/contrib/admin/filters.pyi

@@ -24,7 +24,7 @@ class SimpleListFilter(ListFilter):
     parameter_name: Any = ...
     lookup_choices: Any = ...
     def value(self) -> Optional[str]: ...
-    def lookups(self, request: Any, model_admin: Any) -> None: ...
+    def lookups(self, request: Any, model_admin: Any) -> List[Tuple[Any, str]]: ...
 
 class FieldListFilter(ListFilter):
     field: Field = ...

django-stubs/test/client.pyi

@@ -1,7 +1,7 @@
 from io import BytesIO
 from typing import Any, Dict, List, Optional, Pattern, Tuple, Type, Union
 
-from django.contrib.auth.models import User
+from django.contrib.auth.models import AbstractUser
 from django.contrib.sessions.backends.base import SessionBase
 from django.core.handlers.base import BaseHandler
 from django.core.serializers.json import DjangoJSONEncoder
@@ -113,7 +113,7 @@ class Client:
     @property
     def session(self) -> SessionBase: ...
     def login(self, **credentials: Any) -> bool: ...
-    def force_login(self, user: User, backend: Optional[str] = ...) -> None: ...
+    def force_login(self, user: AbstractUser, backend: Optional[str] = ...) -> None: ...
     def logout(self) -> None: ...
 
 def conditional_content_removal(request: HttpRequest, response: HttpResponseBase) -> HttpResponse: ...