Use specific version of pypi publish image

Author: danielgtaylor

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
         run: pipenv run python setup.py sdist
       - name: Publish package
         if: github.event_name == 'push' && startsWith(github.event.ref, 'refs/tags')
-        uses: pypa/gh-action-pypi-publish@master
+        uses: pypa/gh-action-pypi-publish@v1.0.0a0
         with:
           user: __token__
           password: ${{ secrets.pypi }}