.travis.yml in danger-todoist-1.2.2 vs .travis.yml in danger-todoist-1.2.3

@@ -3,11 +3,16 @@
   directories:
     - bundle
 
 rvm:
   - 2.0
-  - 2.1.3
-  - 2.3.1
+  - 2.1.10
+  - 2.3.3
+  - 2.4.0
+
+before_install:
+  - gem update --system
+  - gem install bundler
 
 before_script:
   - bundle exec danger
 
 script: