Fix build warning

The `res` in authenticate() is not used if
BMCWEB_ENABLE_MUTUAL_TLS_AUTHENTICATION is not enabled.
Add [[maybe_unused]] to tell the compiler to ignore the unused warning.

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Change-Id: I6c73dae67c70572355166a2a0474b26a4dfd46fd
diff --git a/include/authorization.hpp b/include/authorization.hpp
index 04e0223..1c51414 100644
--- a/include/authorization.hpp
+++ b/include/authorization.hpp
@@ -256,8 +256,8 @@
 }
 
 static std::shared_ptr<persistent_data::UserSession> authenticate(
-    boost::asio::ip::address& ipAddress [[maybe_unused]], Response& res,
-    boost::beast::http::verb method,
+    boost::asio::ip::address& ipAddress [[maybe_unused]],
+    Response& res [[maybe_unused]], boost::beast::http::verb method,
     const boost::beast::http::header<true>& reqHeader,
     [[maybe_unused]] const std::shared_ptr<persistent_data::UserSession>&
         session)