Support qwen2 vl model (#1721)

Co-authored-by: yizhang2077 <1109276519@qq.com>
Co-authored-by: ispobock <ISPObaoke@163.com>

python/sglang/srt/conversation.py

@@ -530,3 +530,17 @@ register_conv_template(
         stop_str=["<|im_end|>", "<|action_end|>"],
     )
 )
+
+# Reference: https://huggingface.co/docs/transformers/main/model_doc/qwen2_vl#usage-example
+register_conv_template(
+    Conversation(
+        name="qwen2-vl",
+        system_message="You are a helpful assistant.",
+        system_template="<|im_start|>system\n{system_message}",
+        roles=("<|im_start|>user", "<|im_start|>assistant"),
+        sep="<|im_end|>\n",
+        sep_style=SeparatorStyle.ADD_NEW_LINE_SINGLE,
+        stop_str=["<|im_end|>"],
+        image_token="<|vision_start|><|image_pad|><|vision_end|>",
+    )
+)