Add Node.js 12 to testing (#117)

coreyfarrell · sindresorhus · commit 82db101984fe · 2019-04-29T19:03:46.000+07:00
diff --git a/.travis.yml b/.travis.yml
@@ -4,6 +4,7 @@ os:
   - windows
 language: node_js
 node_js:
+  - '12'
   - '10'
   - '8'
   - '6'
