.travis.yml in appium_lib-9.1.2 vs .travis.yml in appium_lib-9.1.3

@@ -1,9 +1,12 @@
 sudo: false
 cache: bundler
 language: ruby
 rvm:
-  - 2.2.2
+  - 2.2.5
+  - 2.3.3
+  - 2.4.0
+
 before_install: gem update --remote bundler
 install:
   - bundle install --retry=3
 script:
   - bundle exec rake rubocop