Automated release creation failed

[andyasp]

#269 introduced an automated release process that included publishing a release:

      - name: Publish release
        if: github.ref_type == 'tag'
        run: make release-notes | gh release create "$IMAGE_TAG" --notes-file -
        env:
          IMAGE_TAG: ${{ steps.image_tag.outputs.tag }}

When building v0.29.0 (reference) the release step failed with:

gh: To use GitHub CLI in a GitHub Actions workflow, set the GH_TOKEN environment variable. Example:
  env:
    GH_TOKEN: ${{ github.token }}