Use --security-opt label=disable instead of label:disable
Use --security-opt label=disable instead of label:disable

podman only accepts the = syntax.

Fixes #567.

Signed-off-by: Miloslav Trmač <9c008e38982a5397deb855345fb164f0558459ae@redhat.com>

mtrmac/skopeo,mtrmac/skopeo,mtrmac/skopeo,projectatomic/skopeo,projectatomic/skopeo