[CI] Test against Ruby 2.6

DmytroStepaniuk · cyu · commit 145a5df2f1a0 · 2019-03-25T09:58:31.000-04:00
diff --git a/.travis.yml b/.travis.yml
@@ -5,3 +5,4 @@ rvm:
   - 2.3
   - 2.4
   - 2.5
+  - 2.6

-Original file line number
+Diff line change
   - 2.3
   - 2.4
   - 2.5
 +  - 2.6