Merge pull request #245 from flavorjones/flavorjones-fix-ruby-2.5-ci

ci: ensure a min rubygems version

Author: flavorjones

.github/workflows/ci.yml

@@ -39,4 +39,5 @@ jobs:
         with:
           ruby-version: ${{matrix.ruby}}
           bundler-cache: true
+          rubygems: latest
       - run: bundle exec rake test