.travis.yml in hako-2.14.0 vs .travis.yml in hako-2.15.0

@@ -1,14 +1,10 @@
 language: ruby
 sudo: false
 rvm:
-  - 2.3.8
-  - 2.4.6
-  - 2.5.5
-  - 2.6.3
+  - 2.5.8
+  - 2.6.6
+  - 2.7.2
   - ruby-head
-before_install:
-  - gem update --system # https://github.com/rubygems/rubygems/pull/1819
-  - gem install bundler
 matrix:
   allow_failures:
     - rvm: ruby-head