Adjust to 'Final' milestone becoming 'RC' from Fedora 24 on
    
    With Pungi 4 (Fedora 24+), the Final milestone more or less was
    renamed to RC. Mostly let's allow both, but drop 'Final' from
    report-results as no-one should be filing results on 23 or
    earlier any more. Note that wikitcms will, as a kindness, change
    Final to RC for 24+, so asking for '25 Final 1.1' will get you
    25 RC 1.1.