ci(workflow): ensure relative_url is used (#1374)

.github/workflows/ci.yml

@@ -11,5 +11,16 @@ jobs:
           ruby-version: '3.3'
       - name: Install dependencies
         run: bundle install && bundle exec appraisal install
+      - name: Setup Pages
+        id: configure-pages
+        uses: actions/configure-pages@v5
+      - name: Setup CI config
+        run: |
+          echo "---" > _config_ci.yml
+          echo "baseurl: ${{ steps.configure-pages.outputs.base_path }}" >> _config_ci.yml
       - name: Build site
-        run: bundle exec appraisal jekyll build --future
+        env:
+          JEKYLL_ENV: production
+        run: bundle exec appraisal jekyll build --future --config _config_ci.yml,_config.yml
+      - name: Upload artifact
+        uses: actions/upload-pages-artifact@v3