Skip test gems group install in GitHub Actions workflow

We don't need them because we don't run the tests in that workflow.

Author: mokagio

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Install Gems
         run: |
           bundle config path vendor/bundle
-          bundle install --jobs 4 --retry 3
+          BUNDLE_WITHOUT=test bundle install --jobs 4 --retry 3
 
       - name: Run Danger
         run: bundle exec danger