Update gh-pages build workflow to fix YAML syntax issue

Author: sadielbartholomew

.github/workflows/deploy-preview.yml

@@ -45,7 +45,7 @@ jobs:
           mkdir -p public/branch/${{ github.ref_name }}
           cp -R build/* public/branch/${{ github.ref_name }}/
 
-      - name: Debug: show public content
+      - name: Debug to show public content
         run: |
           echo "public tree:"
           ls -laR public || true