ci: only upload tags

.github/workflows/build.yml

@@ -86,9 +86,9 @@ jobs:
           name: tar
           path: dist/setuptools_dso-*.tar.*
       - name: Upload
-        if: github.event_name=='push' && github.ref=='refs/heads/master'
+        if: startsWith(github.ref, 'refs/tags/')
         env:
           TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}
           TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}
         run: |
-          twine upload --skip-existing dist/*
+          twine upload dist/*