Hotfix for simple.yaml (mistype)

  Related-PROD: PROD-36128

Change-Id: I0ce14d5e523d8bc3d8969ec245d1430bf03a3ddd
diff --git a/autoscale/simple.yaml b/autoscale/simple.yaml
index fe95eed..d14f744 100644
--- a/autoscale/simple.yaml
+++ b/autoscale/simple.yaml
@@ -45,4 +45,4 @@
 
 outputs:
   scaleup_policy_signal_url:
-    value: {get_attr: {scaleup_policy, signal_url}}
+    value: {get_attr: [ scaleup_policy, signal_url ]}