test Node.js 8 instead of 7

diff --git a/.travis.yml b/.travis.yml
index c3a6447..aa074a4 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,7 +5,7 @@ sudo: false
 node_js:
   - "4"
   - "6"
-  - "7"
+  - "8"
 
 branches:
   only: