CI: Use 2.6.3

Author: olleolleolle

.travis.yml

@@ -4,7 +4,7 @@ bundler_args: --without tools
 after_success:
   - '[ -d coverage ] && bundle exec codeclimate-test-reporter'
 rvm:
-  - 2.6.2
+  - 2.6.3
   - 2.5.5
   - 2.4.6
   - jruby-9.2.7.0