[PD] Add a fallback to bypass rust dep for mini_lb (#21982)

sgl-model-gateway/bindings/python/src/sglang_router/router_args.py

@@ -4,7 +4,16 @@ import logging
 import os
 from typing import Dict, List, Optional
 
+try:
     from sglang_router.sglang_router_rs import get_available_tool_call_parsers
+except ModuleNotFoundError:
+    logging.warning(
+        "sglang_router_rs is not available, get_available_tool_call_parsers will return empty list"
+    )
+
+    def get_available_tool_call_parsers() -> List[str]:
+        return []
+
 
 logger = logging.getLogger(__name__)