fix: disable attestations for Test PyPI to avoid conflict (#155)

- Disable attestations for Test PyPI publish step
- Keep attestations enabled for production PyPI
- Prevents "attestation files already exist" error when publishing to both

The pypa/gh-action-pypi-publish action creates attestation files (.publish.attestation)
during the first publish. When we try to publish to a second repository in the same
workflow run, it tries to create them again, causing a conflict.

Solution: Disable attestations for Test PyPI (validation only), enable for production.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <[email protected]>

Author: jeremyeder

.github/workflows/release.yml

@@ -79,7 +79,10 @@ jobs:
         uses: pypa/gh-action-pypi-publish@release/v1
         with:
           repository-url: https://test.pypi.org/legacy/
+          attestations: false  # Disable to avoid conflict with production PyPI
 
       - name: Publish to PyPI
         if: steps.check_release.outputs.new_release == 'true'
         uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          attestations: true  # Enable attestations for production