update travisCI config to install bundler 2.x

Todd Campbell · Todd Campbell · commit 925c736adcf0 · 2019-12-19T08:17:23.000-08:00
diff --git a/.travis.yml b/.travis.yml
@@ -2,6 +2,8 @@ language: ruby
 services: docker
 cache:
 - bundler
+before_install:
+- gem install bundler
 install:
 - bundle install
 rvm:
