Bumps [actions/attest-build-provenance](https://github.com/actions/attest-build-provenance) from 1.4.4 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](ef244123eb...7668571508)
Signed-off-by: Derek McGowan <derek@mcg.dev>