Update Travis CI to use Xcode 9 beta 2

thebluepotato · thebluepotato · commit a1b660744001 · 2017-06-30T19:17:46.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,6 @@
 language: objective-c
 rvm: 2.2
-osx_image: xcode8.3
+osx_image: xcode9
 env:
   global:
     - IOS_SIMULATOR="iPhone 6s"
