Bump Node.js version from 6 to 8 on Travis CI (#208)

phillipj · joyeecheung · commit 1f74c03e8d42 · 2019-02-10T12:01:23.000+08:00
As a precursor to upgrading the Node.js version we
run on the github-bot server, this updates the version
used by Travis CI when running our tests.
diff --git a/.travis.yml b/.travis.yml
@@ -1,4 +1,4 @@
 sudo: false
 language: node_js
 node_js:
-  - 6
+  - 8
