ostree/container: add missing --version arg
    
    https://pagure.io/pungi/pull-request/1726 tries to use
    `self.args.version`, but the `pungi-make-ostree container`
    subcommand does not actually have a `--version` arg, so that is
    not going to work. This adds the required arg.
    
    We *could* make it optional by still setting an empty update
    dict if it's not specified, I guess, but not sure if that's worth
    the effort.
    
    Fixes: https://pagure.io/pungi/issue/1751
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>