Urgent model support: support gemma-3-it (#4424)

python/sglang/lang/chat_template.py

@@ -520,6 +520,14 @@ def match_granite_instruct(model_path: str):
         return get_chat_template("granite-3-instruct")
 
 
+@register_chat_template_matching_function
+def match_gemma3_instruct(model_path: str):
+    model_path = model_path.lower()
+    if "gemma-3" in model_path and "1b" not in model_path:
+        # gemma-3-1b-it is completion model
+        return get_chat_template("gemma-it")
+
+
 if __name__ == "__main__":
     messages = [
         {"role": "system", "content": None},  # None means default