build(deps): bump actions/attest-build-provenance (#260)

Bumps the github-actions group with 1 update: [actions/attest-build-provenance](https://github.com/actions/attest-build-provenance).
Updates `actions/attest-build-provenance` from 2.0.1 to 2.1.0
- [Release notes](https://github.com/actions/attest-build-provenance/releases)
- [Changelog](https://github.com/actions/attest-build-provenance/blob/main/RELEASE.md)
- [Commits](actions/attest-build-provenance@c4fbc64...7668571)

Author: dependabot[bot]

.github/workflows/release.yml

@@ -54,7 +54,7 @@ jobs:
         labels: ${{ steps.docker-meta.outputs.labels }}
 
     - name: Attest image
-      uses: actions/attest-build-provenance@c4fbc648846ca6f503a13a2281a5e7b98aa57202  # v2.0.1
+      uses: actions/attest-build-provenance@7668571508540a607bdfd90a87a560489fe372eb  # v2.1.0
       with:
         subject-name: index.docker.io/${{ env.DOCKER_IMAGE_NAME }}
         subject-digest: ${{ steps.docker-push.outputs.digest }}