use a valid nvm version ID instead of the deprecated one

ref. 9972de6dec > `stable`: this alias is deprecated
8 years ago · e4aefe479d
parent 0c9be4bb06
commit e4aefe479d
1 changed files with 1 additions and 1 deletions
--- a/.travis.yml
+++ b/.travis.yml
@ -1,7 +1,7 @@
 language: node_js
 node_js:
  - "6"
-  - "stable"
+  - "node"
 env:
  global:
    - BUILD_TIMEOUT=10000