chore(travis): whitelist greenkeeper branches

greenkeeper[bot] · greenkeeper[bot] · commit 36169cf37945 · 2018-12-09T13:57:35.000Z
diff --git a/.travis.yml b/.travis.yml
@@ -6,6 +6,7 @@ cache: yarn
 branches:
   only:
     - master
+    - /^greenkeeper/.*$/
 script:
   - yarn lint
   - yarn test
