[Frontend] Separate pooling APIs in offline inference (#11129)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

vllm/entrypoints/openai/protocol.py

@@ -900,7 +900,7 @@ class EmbeddingResponse(OpenAIBaseModel):
 class ScoreResponseData(OpenAIBaseModel):
     index: int
     object: str = "score"
-    score: Union[List[float], str]
+    score: float
 
 
 class ScoreResponse(OpenAIBaseModel):