update node version to LTS [skip travis]

ff6347 · ff6347 · commit 4182d1a004fb · 2019-02-13T06:06:19.000+01:00
diff --git a/.travis.yml b/.travis.yml
@@ -6,9 +6,8 @@ cache:
 notifications:
   email: false
 node_js:
-  - '6'
-before_install:
-  - npm i -g npm@^5.6.0
+  - '10'
+
 before_script:
   - npm prune
 script:
