publish.yml: skip-existing on PyPI upload (idempotent re-runs)

Author: Tanvir-Mahmud-Mahim

.github/workflows/publish.yml

@@ -39,3 +39,5 @@ jobs:
           path: dist/
       - name: Publish to PyPI (Trusted Publishing)
         uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          skip-existing: true