win: use modern API

Zhao Yuhang

2023-12-22 adb46e1e151b73e56a7e0066a896b48b92a7230e

 src/core/windowitemdelegate.cpp

@@ -6,6 +6,8 @@

    WindowItemDelegate::~WindowItemDelegate() = default;

    void WindowItemDelegate::resetQtGrabbedControl() const {}
    void WindowItemDelegate::resetQtGrabbedControl(QObject *host) const {
        Q_UNUSED(host);
    }

}