invokeMethod: std::forward universal-ref argument

Spotted in API review

Pick-to: 6.7
Change-Id: I4ab660bb9955176f40b4123e775d65c17edbeeb8
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/kernel/qobjectdefs.h

@@ -620,7 +620,7 @@ private:
                               ExpectedArguments>::value,
                 "Incompatible arguments");
 
-        auto h = QtPrivate::invokeMethodHelper(ret, args...);
+        auto h = QtPrivate::invokeMethodHelper(ret, std::forward<Args>(args)...);
 
         // NOLINTNEXTLINE(clang-analyzer-cplusplus.NewDeleteLeaks)
         auto callable = new QtPrivate::QCallableObject<std::decay_t<Func>, ActualArguments,