Update .travis.yml

Author: Martin Barreto

.travis.yml

@@ -1,7 +1,7 @@
 language: objective-c
-osx_image: xcode9.2
+osx_image: xcode9.3
 env:
-  - DESTINATION="OS=11.0,name=iPhone 8" SCHEME="XLPagerTabStrip" SDK=iphonesimulator
+  - DESTINATION="OS=11.3,name=iPhone 8" SCHEME="XLPagerTabStrip" SDK=iphonesimulator
 before_install:
 - brew update
 #- brew outdated carthage || brew upgrade carthage