correct server chat template

MinerU2.0's chat template during training has additional "\n" compared with chatml's. This difference may slightly affect the performance under server mode. (because sglang_server use sglang's chat template).

mineru/model/vlm_sglang_model/server.py

@@ -6,10 +6,26 @@ from sglang.srt.entrypoints.http_server import app, generate_request, launch_ser
 from sglang.srt.managers.io_struct import GenerateReqInput
 from sglang.srt.server_args import prepare_server_args
 from sglang.srt.utils import kill_process_tree
+from sglang.srt.conversation import Conversation
 
 from mineru.utils.models_download_utils import auto_download_and_get_model_root_path
 from .logit_processor import Mineru2LogitProcessor
 
+# mineru2.0的chat_template与chatml在换行上有微小区别
+def custom_get_prompt(self) -> str:
+    system_prompt = self.system_template.format(system_message=self.system_message)
+    if self.system_message == "":
+        ret = ""
+    else:
+        ret = system_prompt + self.sep
+
+    for role, message in self.messages:
+        if message:
+            ret += role + "\n" + message + self.sep
+        else:
+            ret += role + "\n"
+    return ret
+
 _custom_logit_processor_str = Mineru2LogitProcessor().to_str()
 
 # remote the existing /generate route
@@ -45,6 +61,7 @@ def main():
 
     if server_args.chat_template is None:
         server_args.chat_template = "chatml"
+        Conversation.get_prompt = custom_get_prompt
 
     server_args.enable_custom_logit_processor = True