feat(ci): remove Node.js v4 from .travis.yml

vvakame · vvakame · commit e657ccb2486f · 2018-04-13T16:00:25.000+09:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,5 @@
 language: node_js
 node_js:
-  - 4
   - 6
   - 8
 sudo: false
