[VegetarianOrc]

Summary

• Update both TestPyPI and PyPI publishing jobs to the verified commit for pypa/gh-action-pypi-publish v1.14.3.
• The previous pin bundles validation tooling that rejects Core Metadata 2.5 emitted by the package build.
• Keep metadata verification enabled and retain existing publishing behavior.

Fixes the validation failure in https://github.com/nexus-rpc/sdk-python/actions/runs/40730263356/job/122964684819.

Validation

• Downloaded the actual release-dist artifact from the failed run and checked both the wheel and sdist using twine check --strict with Twine 7.0.0 and packaging 26.2 (the versions bundled by the new action). Both passed.
• Actionlint v1.7.7 passed.
• git diff --check passed.

No publishing workflow was dispatched and no packages were uploaded.