Patch date as well as type for KDE upgrade metadata
    
    For deciding whether to show a release as available for upgrade,
    Discover now also checks its date as well as its 'type'. If the
    date is in the future, even if the type is stable, it won't show
    it unless the allow-pre-releases flag is set.
    
    So, we need to also patch out the date. Just blanking it also
    works, but let's hardcode it to the start of 2025 to be a bit
    more realistic (in case there's ever a situation where the check
    passes with an empty date, but fails with a date it should pass
    with).
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>