Publish on pypi on release event, not push

Author: mgautierfr

.github/workflows/release.yml

@@ -66,7 +66,7 @@ jobs:
           path: ./dist
 
       - name: Push release to PyPI
-        if: github.event_name == 'push' && github.ref == 'refs/heads/master'
+        if: github.event_name == 'release'
         uses: pypa/gh-action-pypi-publish@master
         with:
           user: __token__