.travis.yml in quicktravel_client-3.7.0 vs .travis.yml in quicktravel_client-3.8.0

@@ -2,9 +2,11 @@
 rvm:
   - 2.2
   - 2.3
   - 2.4
   - 2.5
+before_install:
+  - gem install bundler --version "1.17.3"
 script: bundle && bundle exec rake spec
 gemfile:
   - gemfiles/rails4.gemfile
   - gemfiles/rails5.gemfile
 notifications: