Allow fields being an Iterable in bulk_update (#2296)

And `abulk_update`

Author: flaeppe

django-stubs/db/models/manager.pyi

@@ -61,8 +61,8 @@ class BaseManager(Generic[_T]):
         update_fields: Collection[str] | None = ...,
         unique_fields: Collection[str] | None = ...,
     ) -> list[_T]: ...
-    def bulk_update(self, objs: Iterable[_T], fields: Sequence[str], batch_size: int | None = ...) -> int: ...
-    async def abulk_update(self, objs: Iterable[_T], fields: Sequence[str], batch_size: int | None = ...) -> int: ...
+    def bulk_update(self, objs: Iterable[_T], fields: Iterable[str], batch_size: int | None = ...) -> int: ...
+    async def abulk_update(self, objs: Iterable[_T], fields: Iterable[str], batch_size: int | None = ...) -> int: ...
     def get_or_create(self, defaults: Mapping[str, Any] | None = ..., **kwargs: Any) -> tuple[_T, bool]: ...
     async def aget_or_create(self, defaults: Mapping[str, Any] | None = ..., **kwargs: Any) -> tuple[_T, bool]: ...
     def update_or_create(