chore(deps): bump sigstore/scaffolding (kyverno#8522)

Bumps [sigstore/scaffolding](https://github.com/sigstore/scaffolding) from d5eada0a29719b385d26831ead049f188bbfd824 to d21c412f3c2f95421413f43741c2e62c19241dfe.
- [Release notes](https://github.com/sigstore/scaffolding/releases)
- [Changelog](https://github.com/sigstore/scaffolding/blob/main/release.md)
- [Commits](sigstore/scaffolding@d5eada0...d21c412)

---
updated-dependencies:
- dependency-name: sigstore/scaffolding
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/conformance.yaml

@@ -534,7 +534,7 @@ jobs:
         with:
           build-cache-key: run-conformance
       - name: Create kind cluster and setup Sigstore Scaffolding
-        uses: sigstore/scaffolding/actions/setup@d5eada0a29719b385d26831ead049f188bbfd824
+        uses: sigstore/scaffolding/actions/setup@d21c412f3c2f95421413f43741c2e62c19241dfe
       - name: Create TUF values config map
         run: |
           kubectl create namespace kyverno