Add buildVersion as action output (#144) (#145)

src/model/index.js

@@ -4,6 +4,7 @@ import Cache from './cache';
 import Docker from './docker';
 import Input from './input';
 import ImageTag from './image-tag';
+import Output from './output';
 import Platform from './platform';
 import Project from './project';
 import Unity from './unity';
@@ -17,6 +18,7 @@ export {
   Docker,
   Input,
   ImageTag,
+  Output,
   Platform,
   Project,
   Unity,