ConnectionPool on 3.11 takes fewer eventloop cycles because it doesn'…

…t spawn a new task

distributed/tests/test_worker_metrics.py

@@ -599,7 +599,7 @@ async def test_new_metrics_during_heartbeat(c, s, a):
         a.digest_metric(("execute", span.id, "x", "test", "test"), 1)
         await asyncio.sleep(0)
     await hb_task
-    assert n > 10
+    assert n > 9
     await a.heartbeat()
 
     assert a.digests_total["execute", span.id, "x", "test", "test"] == n