.travis.yml in knife-google-3.0.0 vs .travis.yml in knife-google-3.1.0

@@ -2,10 +2,9 @@
 cache: bundler
 sudo: false
 rvm:
 - 2.2.5
 - 2.3.1
-- ruby-head
 branches:
   only:
   - master
 notifications:
   slack: