Call `actor.cancel(None)` from root to avoid mismatch with (any future) meth sig changes

tests/test_advanced_streaming.py

@@ -364,7 +364,6 @@ def test_local_task_fanout_from_stream(
                 'inf_streamer',
                 enable_modules=[__name__],
             )
-            # with trio.fail_after(3):
             async with (
                 p.open_context(inf_streamer) as (ctx, _),
                 ctx.open_stream() as stream,

tractor/_root.py

@@ -343,9 +343,7 @@ async def open_root_actor(
                 #         tempn.start_soon(an.exited.wait)
 
                 logger.cancel("Shutting down root actor")
-                await actor.cancel(
-                    requesting_uid=actor.uid,
-                )
+                await actor.cancel(None)  # self cancel
     finally:
         _state._current_actor = None