Test against Ruby 2.7

Author: stevenharman

.travis.yml

@@ -7,6 +7,7 @@ rvm:
  - 2.4
  - 2.5
  - 2.6
+ - 2.7
 before_script:
  - curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter
  - chmod +x ./cc-test-reporter