.travis.yml in keep_up-0.7.1 vs .travis.yml in keep_up-0.8.0

@@ -5,10 +5,9 @@
   - git config --global user.email "[e-mail]"
   - git config --global user.name "Your Name"
   - gem update --system
 
 rvm:
-  - 2.3
   - 2.4
   - 2.5
   - 2.6
   - ruby-head