Fix formatting: remove trailing whitespace

Author: ddworken

src/mcp/server/streamable_http_manager.py

@@ -343,7 +343,7 @@ async def _run_session_cleanup(self) -> None:
                 # Clean up identified sessions
                 for session_id, idle_time in sessions_to_cleanup:
                     try:
-                        if session_id in self._server_instances:                           
+                        if session_id in self._server_instances:
                             transport = self._server_instances[session_id]
                             logger.info(f"Cleaning up idle session {session_id}")
                             # Terminate the transport to properly close resources