Stabilize merge-ts release job by removing unnecessary BuildKit bootstrap

[Copilot]

merge-ts was failing in Actions due to intermittent timeouts pulling moby/buildkit:buildx-stable-1 during docker/setup-buildx-action. The job only performs manifest assembly/inspection, so this external BuildKit bootstrap dependency was unnecessary.

• Root cause

  • merge-ts invoked docker/setup-buildx-action@v3, which bootstraps BuildKit by pulling from Docker Hub; this pull timed out and failed the job.

• Change

  • Removed the Set up Docker Buildx step from merge-ts in .github/workflows/toolshed.yml.
  • Kept existing digest download, metadata generation, GHCR login, manifest creation, and manifest inspection unchanged.

• Behavioral impact

  • merge-ts no longer depends on Docker Hub availability for BuildKit bootstrap.
  • Manifest publishing path remains the same, with reduced network-flake surface.

merge-ts:
  steps:
    - name: Download digests
      uses: actions/download-artifact@v4
    # removed: docker/setup-buildx-action@v3
    - name: Docker meta
      uses: docker/metadata-action@v5
    - name: Create manifest list and push
      run: docker buildx imagetools create ...

[thirtytwobits]

making release pipeline a bit more stable