Add skip-existing flag to TestPyPI publish step

Co-authored-by: Haydnspass <16120273+Haydnspass@users.noreply.github.com>

Author: Copilot

.github/workflows/publish.yaml

@@ -117,4 +117,5 @@ jobs:
         uses: pypa/gh-action-pypi-publish@release/v1
         with:
           repository-url: https://test.pypi.org/legacy/
+          skip-existing: true
           verbose: true