Unpin node now that a compatible version of jest is out

bb91a124 · Chris Beer · GitHub · cd886107 · bb91a124
Unverified Commit bb91a124 authored Mar 12, 2019 by Chris Beer Committed by GitHub Mar 12, 2019
--- a/.travis.yml
+++ b/.travis.yml
 language: node_js
 node_js:
-  - '11.10.1'
+  - 'node'
 install:
  - npm install -g codecov