add dnf for fedora installation
add dnf for fedora installation

Signed-off-by: Antonio Murdaca <f9809039ea4850e75dcb8d80b778844aa463358f@redhat.com>

mikebrow/skopeo,masters-of-cats/image,containers/image,containers/image,runcom/skopeo,mtrmac/skopeo,estesp/manifest-tool,mtrmac/skopeo,jwhonce/skopeo,mathewkoshy493/manifest-tool,projectatomic/skopeo,estesp/manifest-tool,mtrmac/skopeo,jwhonce/skopeo,mikebrow/skopeo,mathewkoshy493/manifest-tool,projectatomic/skopeo,runcom/skopeo