pkg/asset: Update Calico from 2.6.4 to 2.6.6
pkg/asset: Update Calico from 2.6.4 to 2.6.6

kubernetes-incubator/bootkube,dghubble/bootkube,kubernetes-incubator/bootkube,kubernetes-incubator/bootkube,dghubble/bootkube,dghubble/bootkube