Update reranker/rank_listwise_os_vllm.py to reduce memory footprint

reranker/rank_listwise_os_vllm.py

@@ -44,7 +44,15 @@ class RankListwiseOSLLM(RankLLM):
                 f"Unsupported prompt mode: {prompt_mode}. Only RANK_GPT is supported."
             )
 
-        self._llm = LLM(model=model, max_logprobs=30, enforce_eager=False, gpu_memory_utilization=0.9, max_model_len=32768, trust_remote_code=True, enable_chunked_prefill=True, tensor_parallel_size=1)
+        self._llm = LLM(
+            model=model, max_logprobs=30, 
+            enforce_eager=True, 
+            gpu_memory_utilization=0.9, 
+            max_model_len=2048, 
+            trust_remote_code=True, 
+            enable_chunked_prefill=True, 
+            tensor_parallel_size=1
+        )
         self._tokenizer = self._llm.get_tokenizer()
         self.system_message_supported = "system" in self._tokenizer.chat_template
         self._batched = batched