fix(search): use get_running_loop instead of deprecated get_event_loop

Author: DevanshuNEU

backend/services/search_v3/search_engine.py

@@ -296,7 +296,7 @@ async def _rerank_results(
             documents = [self._format_doc_as_yaml(r) for r in results]
 
             # call Cohere rerank API
-            loop = asyncio.get_event_loop()
+            loop = asyncio.get_running_loop()
             rerank_response = await loop.run_in_executor(
                 None,
                 lambda: self.cohere_client.rerank(