Include `fmf` config in the list of reserved files
    
    Do not remove `fmf` files during `fedpkg import` as these are
    configuration files used for enabling `tmt` tests. See the Fedora
    CI docs for details: https://docs.fedoraproject.org/en-US/ci/tmt/
    
    Resolves https://pagure.io/fedpkg/issue/452
    
    Signed-off-by: Petr Šplíchal <psplicha@redhat.com>