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

src/model/output.test.js

@@ -0,0 +1,9 @@
+import Output from './output';
+
+describe('Output', () => {
+  describe('setBuildVersion', () => {
+    it('does not throw', async () => {
+      await expect(Output.setBuildVersion('1.0.0')).resolves.not.toThrow();
+    });
+  });
+});