update labelsNode to match new labels interface in kube 1.34

[ecordell]

Ran into this when pulling ko in as a library:

# github.com/google/ko/pkg/resolve
pkg/resolve/selector.go:107:26: cannot use labelsNode{…} (value of struct type labelsNode) as labels.Labels value in argument to selector.Matches: labelsNode does not implement labels.Labels (missing method Lookup)
pkg/resolve/selector.go:149:23: cannot use labelsNode{} (value of struct type labelsNode) as labels.Labels value in variable declaration: labelsNode does not implement labels.Labels (missing method Lookup)

I updated the labelsNode implementation to match the new interface. I didn't update the apimachinery dependency in this PR; I'm assuming that ko prefers to track released versions only. This should mean that when it's time to update, there are no conflicts.