.travis.yml in junoser-0.3.13 vs .travis.yml in junoser-0.4.0

@@ -1,10 +1,10 @@
 language: ruby
 
 rvm:
-  - 2.4
-  - 2.5
   - 2.6
+  - 2.7
+  - 3.0
   - ruby-head
 
 before_install:
   - gem update --system
   - gem install bundler