fix PyPI upload issue (#47)

Author: slayoo

.github/workflows/pypi.yml

@@ -40,7 +40,7 @@ jobs:
           repository_url: https://test.pypi.org/legacy/
 
       - if: startsWith(github.ref, 'refs/tags')
-        uses: pypa/gh-action-pypi-publish@master
+        uses: pypa/gh-action-pypi-publish@v1.12.4
         with:
           password: ${{ secrets.PYPI_API_TOKEN }}