.travis.yml in metanorma-m3d-1.2.1 vs .travis.yml in metanorma-m3d-1.2.2

@@ -11,10 +11,10 @@
 - ruby-head
 before_install: 
 - nvm install 8
 - npm install -g puppeteer
 - npm install
-- gem install bundler -v 2.0.1
+- gem install bundler -v "~> 2"
 - bundle update
 matrix:
   allow_failures:
     - rvm: ruby-head