critpath.py: handle Bodhi 'frozen' state
    
    We're not updating critpath for F38 ATM because it's in state
    'frozen' and the script doesn't cope with that. I think only
    development releases will ever be in 'frozen' state, so let's
    assume any release in that state is in the devrels set.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>