Please remove qt5-ukui-platformtheme from unstable.

I am not the maintainer/uploader of qt5-ukui-platformtheme. I am one of the
uploaders of qt6-ukui-platformtheme, namely zhangpan <zhangpan@kylinos.cn>.

From the qt6-ukui-platformtheme side, I do not see any remaining use case for
qt5-ukui-platformtheme. The package appears to be obsolete and superseded by
qt6-ukui-platformtheme.

Please consider removing the source package qt5-ukui-platformtheme and its
binary packages from unstable.

Thanks,
Pan