Test CI for v1.4.1

ci: update sigstore action to fix Windows Python compatibility (#741)

* ci: update sigstore action to fix Windows Python compatibility

Updates sigstore/gh-action-sigstore-python from v3.1.0 to the latest
commit on main branch. This includes the fix from PR #242 which resolves
Python version management issues on Windows runners.

The action now creates its own venv internally using uv and manages
Python versions independently, fixing the dnspython 2.8.0 installation
error that occurred on Windows runners with Python 3.9.

Reference: sigstore/gh-action-sigstore-python#242

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Co-Authored-By: Claude <noreply@anthropic.com>

* upgrade to v1.4.1

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Co-authored-by: Claude <noreply@anthropic.com>