.travis.yml in mini_racer-0.2.6 vs .travis.yml in mini_racer-0.2.7

@@ -1,9 +1,10 @@
 language: ruby
 rvm:
   - 2.3
   - 2.4
   - 2.5
+  - 2.6
   - ruby-head
 matrix:
   include:
     - rvm: 2.5.1
       os: osx