fix(ci): pin third-party GitHub Actions to SHA to prevent supply chain attacks

[memosr]

What does this PR do?

.github/workflows/docker-publish.yml and tests.yml used mutable
version tags for third-party GitHub Actions:

# Before (vulnerable)
uses: docker/build-push-action@v6
uses: astral-sh/setup-uv@v5

Mutable tags can be silently redirected to malicious commits. If an
attacker compromises the docker or astral-sh GitHub organization,
they can push a backdoored commit to the same tag — and the next CI
run will execute it with access to secrets.DOCKERHUB_TOKEN.

Attack scenario

1. Attacker compromises docker/build-push-action and redirects @v6
   to a malicious commit
2. docker-publish.yml runs and the malicious action has access to
   ${{ secrets.DOCKERHUB_TOKEN }} and ${{ secrets.DOCKERHUB_USERNAME }}
3. Attacker pushes a backdoored image as nousresearch/hermes-agent:latest
4. Hundreds of thousands of users pull the compromised image

Fix

Pinned all third-party actions to their full commit SHA with a version
comment for readability:

Action	Old	New
docker/setup-qemu-action	@v3	@SHA # v3
docker/setup-buildx-action	@v3	@SHA # v3
docker/build-push-action	@v6	@SHA # v6
docker/login-action	@v3	@SHA # v3
astral-sh/setup-uv	@v5	@SHA # v5

actions/checkout@v4 (first-party GitHub action) not changed —
first-party actions are trusted.

Type of Change

• 🔒 Security fix (supply chain attack prevention)

Checklist

• Read the Contributing Guide
• Commit messages follow Conventional Commits
• SHA comments preserve version readability
• No behavior change — same action versions, just pinned

[teknium1]

Thanks for the security-conscious contribution, @memosr! 🔒

This is an automated hermes-sweeper review.

The fix you proposed is already reflected on main — both workflow files now use full commit SHA pins with version comments:

• .github/workflows/docker-publish.yml: docker/setup-qemu-action, docker/setup-buildx-action, docker/build-push-action, and docker/login-action are all pinned to full SHAs with # vN comments.
• .github/workflows/tests.yml: astral-sh/setup-uv and actions/checkout are both SHA-pinned.

This PR's changes are fully superseded by the current state of main, so we're closing it. The supply chain hardening you advocated for is in place — appreciate the report!

[alt-glitch]

Superseded by #9801 (merged) — comprehensive supply chain hardening that covers all actions pinned here.