deps: bump sigstore/cosign-installer from 3.7.0 to 3.8.1 (#460)

Bumps [sigstore/cosign-installer](https://github.com/sigstore/cosign-installer) from 3.7.0 to 3.8.1.
- [Release notes](https://github.com/sigstore/cosign-installer/releases)
- [Commits](sigstore/cosign-installer@v3.7.0...v3.8.1)

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

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

Author: dependabot[bot]

.github/workflows/release.yml

@@ -87,7 +87,7 @@ jobs:
       IMAGE_DIGEST: ${{ needs.build.outputs.image-digest }}
     steps:
       - name: Install Cosign
-        uses: sigstore/cosign-installer@v3.7.0
+        uses: sigstore/cosign-installer@v3.8.1
 
       - name: Log into container registry
         uses: redhat-actions/podman-login@v1.7