Fix the dirname command in macOS does not have a -z option

hack/update-go-workspace.sh

@@ -35,6 +35,7 @@ cd "${KUBE_ROOT}"
 # Ensure all modules are included in go.work
 go work edit -use .
 git ls-files -z ':(glob)./staging/src/k8s.io/*/go.mod' \
-    | xargs -0 -n1 dirname -z \
+    | xargs -0 -n1 dirname \
+    | tr '\n' '\0' \
     | xargs -0 -n1 go work edit -use
 go mod download # generate go.work.sum