drop async-service dep and copy relevant code into a local async_service

tool, updated for modern handling of ExceptionGroup

libp2p/pubsub/gossipsub.py

@@ -17,9 +17,6 @@ from typing import (
     Tuple,
 )
 
-from async_service import (
-    Service,
-)
 import trio
 
 from libp2p.network.stream.exceptions import (
@@ -31,6 +28,9 @@ from libp2p.peer.id import (
 from libp2p.pubsub import (
     floodsub,
 )
+from libp2p.tools.async_service import (
+    Service,
+)
 from libp2p.typing import (
     TProtocol,
 )