Update to 1.13.3
    
    While Flatpak should ideally use at least appstream 0.15.3, certain
    practicalities make it difficult to bump the requirement upstream:
      https://github.com/flatpak/flatpak/pull/4949
    
    This reverts 8cbbf308540580010cc153aa89d1e9934ec32888 because the
    downstream patch for gssproxy support doesn't apply anymore and needs
    to be rebased.  Ideally, we shouldn't be in a rush to apply unreviewed
    patches to Rawhide unless there's some major ongoing crisis.