clean up more pedantic compile warnings

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I84790e29a24c73a65c9770c6836b482386cc0ab7
diff --git a/test/message/types.cpp b/test/message/types.cpp
index 327fe71..4020559 100644
--- a/test/message/types.cpp
+++ b/test/message/types.cpp
@@ -4,7 +4,7 @@
 #include <gtest/gtest.h>
 
 template <typename... Args>
-auto dbus_string(Args&&... args)
+auto dbus_string(Args&&... /*args*/)
 {
     return std::string(sdbusplus::utility::tuple_to_array(
                            sdbusplus::message::types::type_id<Args...>())