.travis.yml in junoser-0.3.3 vs .travis.yml in junoser-0.3.4

@@ -1,14 +1,16 @@
 language: ruby
 
 rvm:
-  - 2.1
-  - 2.2
-  - 2.3.1
+  - 2.3
+  - 2.4
+  - 2.5
+  - 2.6
   - ruby-head
 
 before_install:
-  - gem update bundler
+  - gem update --system
+  - gem install bundler
 
 matrix:
   allow_failures:
     - rvm: ruby-head