tool - executors - concurrent - remove no-op gather (strands-agents#954)

Author: pgrayy

src/strands/tools/executors/concurrent.py

@@ -72,8 +72,6 @@ async def _execute(
             yield event
             task_events[task_id].set()
 
-        asyncio.gather(*tasks)
-
     async def _task(
         self,
         agent: "Agent",