Bump actions/attest-build-provenance from 1.4.4 to 2.1.0

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](actions/attest-build-provenance@ef24412...7668571)

---
updated-dependencies:
- dependency-name: actions/attest-build-provenance
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/build.yml

@@ -86,7 +86,7 @@ jobs:
 #        upload-release-assets: ${{ runner.os == 'Windows' }}
 
     - name: Attest artifacts
-      uses: actions/attest-build-provenance@ef244123eb79f2f7a7e75d99086184180e6d0018 # v1.4.4
+      uses: actions/attest-build-provenance@7668571508540a607bdfd90a87a560489fe372eb # v2.1.0
       if: |
         runner.os == 'Windows' &&
         github.event.repository.fork == false &&