Pin PyPI release actions to immutable commits

[parkjinman98]

Motivation

• The release workflow used mutable action refs (tags/branches) while granting id-token: write, creating a supply-chain risk that a compromised upstream action could publish arbitrary packages to PyPI.
• Pinning actions to reviewed full commit SHAs ensures the code executed in OIDC-enabled publish jobs is auditable and cannot be silently altered by retargeting tags.

Description

• Replaced every mutable uses: reference in .github/workflows/publish.yml with a 40-hex commit SHA pointing at the reviewed action commit while preserving a human-readable version comment for future updates.
• Action pins include actions/checkout, actions/setup-python, actions/upload-artifact, actions/download-artifact, and pypa/gh-action-pypi-publish in both TestPyPI and PyPI jobs.
• The change only modifies the single workflow file to enforce immutable action resolution and does not alter any build, upload, or publish logic.

Testing

• Ran a custom audit script that validated all seven uses: references in .github/workflows/publish.yml are full 40-character commit SHAs and it succeeded.
• Ran git diff --check and confirmed no whitespace/check errors, and git status --short to confirm the working tree is clean after committing the change.
• Attempted pre-commit run --files .github/workflows/publish.yml, but pre-commit was not installed in the environment (noted as informational, not a failure).

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Codex Task

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-11T04:10:46.500558Z	2dc8bc0	PR opened

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[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 2dc8bc089c

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[chatgpt-codex-connector]

Pin the current action majors instead of downgrading them

This SHA is upload-artifact v4.6.2 rather than an immutable pin for the previously selected v7; the same change downgrades download-artifact from v7 to v4.3.0, checkout from v5 to v4.2.2, and setup-python from v6 to v5.6.0. Consequently, the next release silently runs older action generations and loses the compatibility and security fixes for which the workflow had selected the newer majors, rather than merely making its existing dependencies immutable. Resolve each original major tag to its reviewed commit SHA and pin that commit.

Useful? React with 👍 / 👎.