Cleanup kubernetes 1.15.x hashes (and references) as it has now reached EOL (#5876)
Cleanup kubernetes 1.15.x hashes (and references) as it has now reached EOL (#5876)


kubernetes-incubator/kargo,kubernetes-sigs/kubespray,Atoms/kubespray,kubernetes-sigs/kubespray,Atoms/kubespray,kubernetes-incubator/kubespray,kubernetes-sigs/kubespray,Atoms/kubespray,kubernetes-incubator/kubespray,kubernetes-incubator/kargo,kubernetes-sigs/kubespray,Atoms/kubespray