aioble/multitests: Store a reference to return value of create_task.

As required by CPython, and enforced by Ruff RUF006.

Signed-off-by: Damien George <[email protected]>

micropython/bluetooth/aioble/multitests/ble_write_order.py

@@ -44,12 +44,12 @@ async def instance0_task():
 
     # Register characteristic.written() handlers as asyncio background tasks.
     # The order of these is important!
-    asyncio.create_task(task_written(characteristic_second, "second"))
-    asyncio.create_task(task_written(characteristic_first, "first"))
+    task_second = asyncio.create_task(task_written(characteristic_second, "second"))
+    task_first = asyncio.create_task(task_written(characteristic_first, "first"))
 
     # This dummy task simulates background processing on a real system that
     # can block the asyncio loop for brief periods of time
-    asyncio.create_task(task_dummy())
+    task_dummy = asyncio.create_task(task_dummy())
 
     multitest.globals(BDADDR=aioble.config("mac"))
     multitest.next()