Add ruby 2.5.3

cintamani · web-flow · commit f608aef83c85 · 2018-11-07T10:47:20.000Z
Add the latest stable ruby version in the list of RVM to test
diff --git a/.travis.yml b/.travis.yml
@@ -29,6 +29,7 @@ rvm:
   - 2.2.8
   - 2.3.5
   - 2.4.2
+  - 2.5.3
   - ruby-head
 
 branches:
