`virtcontainers-setup.sh` does not have #!/bin/bash on the first line

[grahamwhaley]

in virtcontainers-setup.sh at https://github.com/containers/virtcontainers/blob/master/utils/virtcontainers-setup.sh#L17 we have the #!/bin/bash down on line 17, when it needs to be on line 0. Fix it!