chore(travis): try ruby 2.2 because of build failure

mediumTaj · mediumTaj · commit f362559e22ed · 2018-08-03T09:00:37.000-05:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,7 +1,7 @@
 language: objective-c
 osx_image: xcode61
 rvm:
-- 2.1.2
+- 2.2
 cache:
   directories:
     - ./Unity
