Update upgrades.md (#7361)
Update upgrades.md (#7361)

upgrades.md explains how to do upgrade from v1.4.3 to v1.4.6 as an
example. The versions are a little old, and the doc readers would
have a concern the upgrade works fine or not.
This updates versions after verifying the way works fine by hands.
kubernetes-incubator/kargo,kubernetes-sigs/kubespray,Atoms/kubespray,Atoms/kubespray,kubernetes-incubator/kubespray,Atoms/kubespray,Atoms/kubespray,kubernetes-sigs/kubespray,kubernetes-sigs/kubespray,kubernetes-incubator/kubespray,kubernetes-incubator/kargo,kubernetes-sigs/kubespray