.travis.yml in percy-common-1.5.0 vs .travis.yml in percy-common-2.0.0

@@ -1,9 +1,9 @@
 language: ruby
 sudo: false
 cache: bundler
 rvm:
-  - 2.2.5
+  - 2.4
   - ruby-head
 before_install:
   - gem update bundler
 script:
   - bundle exec rubocop -D