tier-x: explicitly list podman, skopeo

They're such important tools to the experience, it's weird to leave it
as being it implied by bootc only.

tier-x/manifest.yaml

@@ -13,6 +13,9 @@ packages:
   # crun recommends but doesn't require criu and criu-libs. We want them for
   # checkpoint/restore. https://github.com/coreos/fedora-coreos-tracker/issues/1370
   - criu criu-libs
+  # deps of bootc, but let's be explicit. e.g. even if bootc drops the skopeo
+  # dep, we still want it
+  - podman skopeo
   # storage
   - cryptsetup
   - lvm2