[CHORE] Switch workflow attestation action to actions/attest

[c-vigo]

Chore Type

CI / Build change

Description

Migrate workflow attestation from actions/attest-build-provenance to actions/attest, per upstream guidance noted in PR #65.
As of v4, attest-build-provenance is a wrapper around actions/attest, and new implementations should use actions/attest directly.

Acceptance Criteria

• Replace actions/attest-build-provenance usage with actions/attest in relevant workflow file(s)
• Preserve existing attestation behavior (artifact subject, provenance generation, and permissions scope)
• Validate workflow syntax and successful execution in CI
• Document any required input/permission changes in workflow comments or docs (if applicable)

Implementation Notes

• Scope is limited to GitHub Actions workflow attestation steps.
• Review differences in action inputs between wrapper action and actions/attest.
• Keep least-privilege permissions for workflow tokens.

Related Issues

Related to PR #65

Priority

Medium

Changelog Category

No changelog needed

Additional Context

PR #65 updates actions/attest-build-provenance and includes upstream release guidance:
“new implementations should use actions/attest instead.”