Fix annotation

Co-authored-by: Thomas Grainger <tagrain@gmail.com>

distributed/cli/utils.py

@@ -8,7 +8,7 @@
 logger = logging.getLogger(__name__)
 
 
-async def wait_for_signals(signals: list[signal.Signals]):
+async def wait_for_signals(signals: list[signal.Signals]) -> None:
     """Wait for the passed signals by setting global signal handlers"""
     loop = asyncio.get_running_loop()
     event = asyncio.Event()