add default versions to preload generation

hack/preload-images/preload_images.go

@@ -26,6 +26,7 @@ import (
 	"strings"
 
 	"github.com/spf13/viper"
+	"k8s.io/minikube/pkg/minikube/constants"
 	"k8s.io/minikube/pkg/minikube/download"
 )
 
@@ -72,6 +73,8 @@ func main() {
 		}
 	}
 
+	k8sVersions = append(k8sVersions, constants.DefaultKubernetesVersion, constants.NewestKubernetesVersion, constants.OldestKubernetesVersion)
+
 	for _, kv := range k8sVersions {
 		for _, cr := range containerRuntimes {
 			tf := download.TarballName(kv, cr)