chore: add a deploy key to allow pushing to main (#9642)

Author: maribethb

.github/workflows/publish.yml

@@ -79,6 +79,7 @@ jobs:
         uses: actions/checkout@v5
         with:
           fetch-depth: 0
+          ssh-key: ${{ secrets.DEPLOY_PRIVATE_KEY }}
 
       - name: Download versioned files
         uses: actions/download-artifact@v4