spec file: bump python-netaddr Requires
    
    Bump python-netaddr Requires to the version which has correct private and
    reserved IPv4 address ranges.
    
    This fixes DNS server install failure when 0.0.0.0 is entered as a
    forwarder.
    
    https://pagure.io/freeipa/issue/6894
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>