推理结果不变，每次同样的图像，同样的问题，答案都一样。如何答案多样性？

[xiaowenhe]

`import os
os.environ['CUDA_VISIBLE_DEVICES'] = '0'
os.environ['MAX_PIXELS'] = '1003520'
os.environ['VIDEO_MAX_PIXELS'] = '50176'
os.environ['FPS_MAX_FRAMES'] = '12'

from swift.llm import PtEngine, RequestConfig, InferRequest
model = 'Qwen/Qwen2.5-VL-7B-Instruct'

engine = PtEngine(model, max_batch_size=2)
request_config = RequestConfig(max_tokens=512, temperature=0)

infer_requests = [
InferRequest(messages=[{'role': 'user', 'content': '对该图像进行描述'}],
images=['xxxx.png'])
]
resp_list = engine.infer(infer_requests, request_config)
query0 = infer_requests[0].messages[0]['content']
print(f'response0: {resp_list[0].choices[0].message.content}')`

使用上述代码进行推理，每次答案都一样，没有多样性，请问如何才能使答案多样性？谢谢！