Use Xcode10 on Travis CI

Kuniwak · Kuniwak · commit 40cf98c1711b · 2018-09-29T10:19:42.000+09:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,6 @@
 ---
 language: swift
-osx_image: xcode9.4
+osx_image: xcode10
 xcode_project: TDDBCSwift.xcodeproj
 xcode_scheme: TDDBCSwiftTests
 xcode_destination: platform=iOS Simulator,OS=11.3,name=iPhone X
