修复ppo报错

backend/app/engines/text_engine.py

@@ -323,7 +323,8 @@ class TextEngine(BaseEngine):
             self._model = AutoModelForCausalLMWithValueHead.from_pretrained(
                 self._model, peft_config=peft_config,
             )
-            self._model.print_trainable_parameters()
+            if hasattr(self._model, "print_trainable_parameters"):
+                self._model.print_trainable_parameters()
 
             # TRL 0.9.x PPOConfig 只接受 PPO 专用参数，不支持 HuggingFace Trainer 参数
             # mini_batch_size 必须满足：batch_size % (mini_batch_size * gradient_accumulation_steps) == 0