[Model] Add Idefics3 support (#9767)

Signed-off-by: Jee Jee Li <pandaleefree@gmail.com>
Signed-off-by: B-201 <Joy25810@foxmail.com>
Co-authored-by: B-201 <Joy25810@foxmail.com>

vllm/entrypoints/chat_utils.py

@@ -187,6 +187,8 @@ class BaseMultiModalItemTracker(ABC, Generic[_T]):
                 return "<|vision_start|><|image_pad|><|vision_end|>"
             if model_type == "molmo":
                 return ""
+            if model_type == "idefics3":
+                return "<image>"
 
             raise TypeError(f"Unknown {modality} model type: {model_type}")
         elif modality == "audio":