Change default branch to main

Author: Verweijen

.github/workflows/sphinx.yml

@@ -19,7 +19,7 @@ jobs:
         path: docs/build/html/
     - name: Deploy
       uses: peaceiris/actions-gh-pages@v3
-      if: github.ref == 'refs/heads/package'
+      if: github.ref == 'refs/heads/main'
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}
         publish_dir: docs/build/html