Bump sigstore/cosign-installer from 2.8.0 to 2.8.1

Bumps [sigstore/cosign-installer](https://github.com/sigstore/cosign-installer) from 2.8.0 to 2.8.1.
- [Release notes](https://github.com/sigstore/cosign-installer/releases)
- [Commits](https://github.com/sigstore/cosign-installer/compare/v2.8.0...v2.8.1)

---
updated-dependencies:
- dependency-name: sigstore/cosign-installer
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

.github/workflows/ci.yaml

@@ -441,7 +441,7 @@ jobs:
             jq -s '.[0] * .[1]' ${{ steps.meta.outputs.bake-file }} ${{ steps.meta-debug.outputs.bake-file }} > docker-bake.override.json
 
       - name: Setup Cosign
-        uses: sigstore/cosign-installer@v2.8.0
+        uses: sigstore/cosign-installer@v2.8.1
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v2