Regenerate inventory file when config changes

Change-Id: Ie8bb9b0a957db3d51fbcf0d0f6620e9c0b4eb63c
diff --git a/build.gradle b/build.gradle
index f72dd13..db86e6d 100644
--- a/build.gradle
+++ b/build.gradle
@@ -57,6 +57,8 @@
 }
 
 task copyAnsibleInventory(type: Copy) {
+    inputs.file deployConfig
+
     File configFile = new File(deployConfig)
     def yaml = new Yaml()
     def config = yaml.load(configFile.newReader())