Merge pull request #57 from olleolleolle/patch-1

CI: use 2.4.6, 2.6.3, jruby-9.2.7.0, drop 2.3.8 (EOL)

Author: solnic

.travis.yml

@@ -4,11 +4,10 @@ bundler_args: --without tools
 after_success:
   - '[ -d coverage ] && bundle exec codeclimate-test-reporter'
 rvm:
-  - 2.6.2
+  - 2.6.3
   - 2.5.5
-  - 2.4.5
-  - 2.3.8
-  - jruby-9.2.6.0
+  - 2.4.6
+  - jruby-9.2.7.0
   - truffleruby
 matrix:
   allow_failures: