chore(ci): test oldest and latest Ruby versions only

DirtyF · DirtyF · commit 557cebc4e469 · 2018-12-06T11:52:51.000+01:00
diff --git a/.travis.yml b/.travis.yml
@@ -8,7 +8,6 @@ matrix:
       env: GH_PAGES=true
 rvm:
   - 2.5
-  - 2.4
   - 2.3
 before_install:
 - gem update --system
