CI: use 2.6.2, 2.5.5

Author: olleolleolle

.travis.yml

@@ -4,8 +4,8 @@ bundler_args: --without tools
 after_success:
   - '[ -d coverage ] && bundle exec codeclimate-test-reporter'
 rvm:
-  - 2.6.1
-  - 2.5.3
+  - 2.6.2
+  - 2.5.5
   - 2.4.5
   - 2.3.8
   - jruby-9.2.6.0