win: use modern API

Zhao Yuhang

2023-12-22 adb46e1e151b73e56a7e0066a896b48b92a7230e

 src/quick/quickwindowagent.cpp

@@ -32,9 +32,7 @@
            return false;
        }

        if (!d->setup(window, new QuickItemDelegate())) {
            return false;
        }
        d->setup(window, new QuickItemDelegate());
        d->hostWindow = window;

#ifdef Q_OS_WINDOWS