Update run_tests.sh to the latest revision

Change-Id: I58b033e2eb28f0a3ba7ecd90719fc55e7774fe37
diff --git a/metadata.yml b/metadata.yml
index e643fae..b2edf1a 100644
--- a/metadata.yml
+++ b/metadata.yml
@@ -1,3 +1,6 @@
 name: "horizon"
 version: "2016.4.1"
 source: "https://github.com/openstack/salt-formula-horizon"
+dependencies:
+  - name: linux
+    source: "https://github.com/salt-formulas/salt-formula-linux"