Drop support for node version older than 6

DominikPalo · web-flow · commit af332413f565 · 2018-11-22T23:45:45.000+01:00
Versions older than node 6 are no longer supported by html-webpack-plugin version 4. See: jantimon/html-webpack-plugin#861
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,7 @@
 language: node_js
 node_js:
-  - "4"
-  - "5"
+  - stable
+  - lts/*
+  - 6.9
 script:
   - npm test
