travis config update

.travis.yml

@@ -1,17 +1,12 @@
 language: swift
-osx_image: xcode10
+osx_image: xcode10.2
 xcode_project: BookPlayer.xcodeproj
 xcode_scheme: BookPlayer
 xcode_destination: platform=iOS Simulator,OS=11.3,name=iPhone 5s
 cache:
   directories:
   - Carthage
   - $HOME/Library/Caches/Homebrew
-before_install:
-  - brew update
-  - brew outdated carthage || brew upgrade carthage
 before_script:
-  # bootstrap the dependencies for the project
-  # you can remove if you don't have dependencies
   - carthage bootstrap --no-use-binaries --platform iOS --cache-builds
   - swiftlint