fix deploy

Author: vk2seb

.github/workflows/deploy.yaml

@@ -21,7 +21,7 @@ jobs:
         run: pdm build-site
       - name: Deploy to GitHub Pages
         uses: peaceiris/actions-gh-pages@v4
-        if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/master' }}
+        if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' }}
         with:
           publish_branch: gh-pages
           github_token: ${{ secrets.GITHUB_TOKEN }}