Add Salt 2018.3 tests

Change-Id: I674e10d679875b8629191284e0f92d405941bf2b
diff --git a/.kitchen.yml b/.kitchen.yml
index f939ef3..5bca6a9 100644
--- a/.kitchen.yml
+++ b/.kitchen.yml
@@ -53,7 +53,7 @@
 platforms:
   - name: <%= ENV['PLATFORM'] || 'saltstack-ubuntu-xenial-salt-stable' %>
     driver_config:
-      image: <%= ENV['PLATFORM'] || 'epcim/salt-formulas:saltstack-ubuntu-xenial-salt-stable' %>
+      image: <%= ENV['PLATFORM'] || 'epcim/salt:saltstack-ubuntu-xenial-salt-stable' %>
       platform: ubuntu
 
 suites: