[nits] fix ruff

Author: jeffreysijuntan

rllm/trainer/agent_sft_trainer.py

@@ -14,6 +14,7 @@
 
 logger = logging.getLogger(__name__)
 
+
 class RLLMSFTDataset(MultiTurnSFTDataset):
     def __init__(self, parquet_files: str | list[str], tokenizer, config=None):
         super().__init__(parquet_files, tokenizer, config)
@@ -185,4 +186,4 @@ def process_trajectories(trajectories: list[Trajectory], reward_threshold: float
 
     def train(self):
         """Start training."""
-        self.run_sft()
+        self.run_sft()