Update .travis.yml

Christian Kröger · web-flow · commit fb597b8520de · 2018-07-03T14:06:27.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,8 @@
 language: ruby
 rvm:
-  - 2.3.0
+  - 2.3
+  - 2.4
+  - 2.5
 after_success: coveralls
 notifications:
   email:
