Add auth to get server info (#10751)

Co-authored-by: Xinyuan Tong <115166877+JustinTong0323@users.noreply.github.com>

python/sglang/bench_serving.py

@@ -1763,7 +1763,9 @@ async def benchmark(
         pbar.close()
 
     if "sglang" in backend:
-        server_info = requests.get(base_url + "/get_server_info")
+        server_info = requests.get(
+            base_url + "/get_server_info", headers=get_auth_headers()
+        )
         if server_info.status_code == 200:
             server_info_json = server_info.json()
             if "decode" in server_info_json: