Use Xcode GM, per https://docs.travis-ci.com/user/osx-ci-environment/

fulldecent · fulldecent · commit bdfc11ab8aa5 · 2017-04-15T03:37:41.000+08:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,5 +1,5 @@
 language: objective-c
-osx_image: xcode8.3
+osx_image: xcode8
 env:
   global:
   - LC_CTYPE=en_US.UTF-8
