Update ruby.yml

Author: gaborbata

.github/workflows/ruby.yml

@@ -26,7 +26,7 @@ jobs:
     # uses: ruby/setup-ruby@v1
       uses: ruby/setup-ruby@473e4d8fe5dd94ee328fdfca9f8c9c7afc9dae5e
       with:
-        ruby-version: 2.6
+        ruby-version: 3.0
     - name: Install dependencies
       run: bundle install
     - name: Run tests