Fix fallback subscriptions for old HA versions (#343)

matter_server/server/device_controller.py

@@ -520,7 +520,7 @@ async def _subscribe_node(self, node_id: int) -> None:
             # individual subscriptions (e.g. bridges)
             attr_subscriptions = "*"  # type: ignore[assignment]
 
-        if node.attribute_subscriptions == []:
+        if not node.attribute_subscriptions:
             # temp fix for backwards compatbility with HA releases below 2023.7
             # fallback to wildcard subscriptions if we have no explicit
             # node subscriptions defined.