allow steam running as root, use `opus-nano`, remove `vulkan-swrast`

There is no point in adding `vulkan-swrast`, any game will just be too slow with it, and people just get confused like it has happened before that they say that games are running too slow when it defaults to using that. running steam as root is a fix for https://github.com/pkgforge-dev/Anylinux-AppImages/issues/16