Update Ruby version

.travis.yml

@@ -2,7 +2,7 @@ language: ruby
 sudo: required
 cache: bundler
 rvm:
-  - 2.3.4
+  - 2.3.5
 services:
   - docker
 script:

Gemfile

@@ -1,5 +1,5 @@
 source 'https://rubygems.org'
-ruby '2.3.4'
+ruby '2.3.5'
 
 gem 'test-kitchen'
 gem 'kitchen-docker'