Match travis and Gemfile ruby version.

Author: jpsacha

.travis.yml

@@ -2,6 +2,9 @@ language: ruby
 cache: bundler
 sudo: false
 rvm:
-- 2.6.1
-before_script: gem install bundler:2.0.1; bundle install
+  - 2.6.1
+before_script:
+  - bundle update --bundler
+  - gem install bundler:2.0.1
+  - bundle install
 script: "bundle exec jekyll build"