Simplify bundle format and set repo_releasever correctly
    
    Pungi now automatically sets the version for the kiwibuild phase
    based on the configuration, so this is now automatically propagated.
    
    Additionally, now the repo_releasever needs to be set correctly,
    since version is now set by Pungi automatically.
    
    Signed-off-by: Neal Gompa <ngompa@fedoraproject.org>