.travis.yml in yard-sorbet-0.0.1 vs .travis.yml in yard-sorbet-0.1.0

@@ -1,7 +1,8 @@
 ---
 language: ruby
+cache: bundler
 rvm:
-  - 2.4
   - 2.5
   - 2.6
   - 2.7
+before_install: gem install bundler -v 2.1.4