Fix error in k8s cluster after deletion

- Now if you delete the cluster from the UI or Cli, when you run again the plan or apply command, the resource will be recreate if not found

#16

civo/resource_kubernetes_cluster.go

@@ -220,7 +220,7 @@ func resourceKubernetesClusterRead(d *schema.ResourceData, m interface{}) error
 	log.Printf("[INFO] retrieving the kubernetes cluster %s", d.Id())
 	resp, err := apiClient.FindKubernetesCluster(d.Id())
 	if err != nil {
-		if resp != nil {
+		if resp == nil {
 			d.SetId("")
 			return nil
 		}