fix import error

src/llmtuner/tuner/rm/workflow.py

@@ -3,6 +3,7 @@
 # https://github.com/CarperAI/trlx/blob/main/examples/summarize_rlhf/reward_model/train_reward_model_gptj.py
 
 from typing import TYPE_CHECKING, Optional, List
+from transformers import Seq2SeqTrainingArguments
 
 from llmtuner.dsets import get_dataset, preprocess_dataset, split_dataset
 from llmtuner.extras.ploting import plot_loss
@@ -12,7 +13,7 @@ from llmtuner.tuner.rm.collator import PairwiseDataCollatorWithPadding
 from llmtuner.tuner.rm.trainer import PairwisePeftTrainer
 
 if TYPE_CHECKING:
-    from transformers import Seq2SeqTrainingArguments, TrainerCallback
+    from transformers import TrainerCallback
     from llmtuner.hparams import ModelArguments, DataArguments, FinetuningArguments