Only test on modern versions of Ruby

Author: wildlyinaccurate

.travis.yml

@@ -5,8 +5,8 @@ bundler_args: --without debug
 before_script: bundle exec jekyll --version
 script: bundle exec rake features_with_coveralls
 rvm:
+  - '2.6'
+  - '2.5'
   - '2.4'
   - '2.3'
   - '2.2'
-  - '2.1'
-  - '2.0'