.travis.yml in validate_zipcode-1.2.0 vs .travis.yml in validate_zipcode-1.2.1

@@ -1,4 +1,7 @@
 language: ruby
 rvm:
-  - 2.2.4
-before_install: gem install bundler -v 1.11.2
+  - 2.2.3
+  - 2.3.1
+
+before_install:
+  - gem update bundler