Update Travis CI and README

.travis.yml

@@ -4,13 +4,13 @@ os:
 language: generic
 sudo: required
 dist: trusty
-osx_image: xcode9.2
+osx_image: xcode9.3beta
 install:
 - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then
     eval "$(curl -sL https://gist.githubusercontent.com/kylef/5c0475ff02b7c7671d2a/raw/9f442512a46d7a2af7b850d65a7e9bd31edfb09b/swiftenv-install.sh)";
-    swiftenv install 4.0.3;
-    swiftenv global 4.0.3;
-    export LD_LIBRARY_PATH=$HOME/.swiftenv/versions/4.0.3/usr/lib/swift/linux:$LD_LIBRARY_PATH;
+    swiftenv install 4.1;
+    swiftenv global 4.1;
+    export LD_LIBRARY_PATH=$HOME/.swiftenv/versions/4.1/usr/lib/swift/linux:$LD_LIBRARY_PATH;
   fi
 - swift --version
 script:

README.md

@@ -6,7 +6,7 @@
 
 [![Travis CI Status](https://api.travis-ci.org/yanagiba/swift-transform.svg?branch=master)](https://travis-ci.org/yanagiba/swift-transform)
 [![codecov](https://codecov.io/gh/yanagiba/swift-transform/branch/master/graph/badge.svg)](https://codecov.io/gh/yanagiba/swift-transform)
-![Swift 4.0](https://img.shields.io/badge/swift-4.0-brightgreen.svg)
+![Swift 4.1](https://img.shields.io/badge/swift-4.1-brightgreen.svg)
 ![Swift Package Manager](https://img.shields.io/badge/SPM-ready-orange.svg)
 ![Platforms](https://img.shields.io/badge/platform-%20Linux%20|%20macOS%20-red.svg)
 ![License](https://img.shields.io/github/license/yanagiba/swift-transform.svg)
@@ -28,7 +28,7 @@ Please also check out the [status](https://github.com/yanagiba/swift-ast#a-work-
 
 ## Requirements
 
-- [Swift 4.0](https://swift.org/download/)
+- [Swift 4.1](https://swift.org/download/)
 
 ## Development