testing/uranium: fix cura

This fixes uranium for cura until !46012 is merged:

• ports Fedora's patch: https://src.fedoraproject.org/rpms/python-uranium/blob/rawhide/f/Uranium-5.3.0-qt-try-ints-then-bytes-for-gl-mask-functions.patch
• backports SimpleButton fix from https://github.com/Ultimaker/Uranium/pull/874

Without this, cura crashes or starts without UI.