Fixing auto_scaler issue with root node pool in athens cluster

infra/vultr-kubernetes/cluster.tf

@@ -10,6 +10,7 @@ resource vultr_kubernetes athens {
     label         = var.cluster.pools["main"].label
     min_nodes     = var.cluster.pools["main"].min_nodes
     max_nodes     = var.cluster.pools["main"].max_nodes
+    auto_scaler   = true
   }
 }