Update pool.py

Author: gridnevvvit

ydb/aio/pool.py

@@ -34,7 +34,7 @@ async def get(self, preferred_endpoint=None, fast_fail=False, wait_timeout=10):
             return self.connections_by_node_id[preferred_endpoint.node_id]
 
         if preferred_endpoint is not None and preferred_endpoint.endpoint in self.connections:
-            return self.connections[preferred_endpoint]
+            return self.connections[preferred_endpoint.endpoint]
 
         for conn_lst in self.conn_lst_order:
             try: