Remove unnecessary assertion in test_when_timeout_smaller_second (#11537)

Author: Cycloctane

tests/test_helpers.py

@@ -297,7 +297,6 @@ def test_when_timeout_smaller_second(loop: asyncio.AbstractEventLoop) -> None:
     timer = loop.time() + timeout
 
     handle = helpers.TimeoutHandle(loop, timeout)
-    assert handle is not None
     start_handle = handle.start()
     assert start_handle is not None
     when = start_handle.when()