Update workflow to only publish the default branch

Author: bryannielsen

.github/workflows/publish.yml

@@ -25,6 +25,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v3
       - name: Setup Pages
+        if: github.ref_name == github.event.repository.default_branch
         uses: actions/configure-pages@v2
       - name: Set up node version
         uses: actions/setup-node@v2
@@ -39,6 +40,7 @@ jobs:
         with:
           path: 'build'
   deploy:
+    if: github.ref_name == github.event.repository.default_branch
     environment:
       name: github-pages
       url: ${{ steps.deployment.outputs.page_url }}