修改train_model_grpo.py代码，验证GRPO训练模型，输出训练用数据集为jsonl文件，保存至data/backup相对路径

src/train_model_grpo.py

@@ -56,6 +56,9 @@ def get_gsm8k_questions(split = "train") -> Dataset:
 
 dataset = get_gsm8k_questions()
 
+# 方法 1：使用 datasets 库的 to_json 方法
+dataset.to_json(os.path.join("..","data","backup", "gsm8k_dataset_for_train.jsonl"), orient="records", lines=True, force_ascii=False)
+
 # Reward functions
 def correctness_reward_func(prompts, completions, answer, **kwargs) -> list[float]:
     responses = [completion[0]['content'] for completion in completions]