build(deps): bump slsa-framework/slsa-github-generator

Bumps [slsa-framework/slsa-github-generator](https://github.com/slsa-framework/slsa-github-generator) from 2.0.0 to 2.1.0.
- [Release notes](https://github.com/slsa-framework/slsa-github-generator/releases)
- [Changelog](https://github.com/slsa-framework/slsa-github-generator/blob/main/CHANGELOG.md)
- [Commits](https://github.com/slsa-framework/slsa-github-generator/compare/v2.0.0...v2.1.0)

---
updated-dependencies:
- dependency-name: slsa-framework/slsa-github-generator
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/build-push-image.yml

@@ -209,7 +209,7 @@ jobs:
       actions: read # for detecting the Github Actions environment.
       id-token: write # for creating OIDC tokens for signing.
       packages: write # for uploading attestations.
-    uses: slsa-framework/slsa-github-generator/.github/workflows/generator_container_slsa3.yml@v2.0.0
+    uses: slsa-framework/slsa-github-generator/.github/workflows/generator_container_slsa3.yml@v2.1.0
     with:
       digest: ${{ needs.merge.outputs[format('digest_{0}', matrix.manifest_type)] }}
       image: ${{ needs.merge.outputs.image }}