We need an F32 desktop image for aarch64
    
    This is for
    https://pagure.io/fedora-qa/os-autoinst-distri-fedora/issue/201 -
    we're working around that by using the F32 image for now, but it
    doesn't exist on aarch64 ATM. We'll have to remember to take
    this out when that's fixed.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>