Update async keyboard code

... per adafruit/circuitpython#8412
Otherwise this is incompatible with both 8.x and 9.

Author: jepler

CircuitPython_Commodore_16_KB2040/advanced/code.py

@@ -142,7 +142,7 @@ def __init__(self, events):
         self._events = events
 
     async def __await__(self):
-        yield asyncio.core._io_queue.queue_read(self._events)
+        await asyncio.core._io_queue.queue_read(self._events)
         return self._events.get()
 
     def __enter__(self):