Bump sigstore/cosign-installer from 3.7.0 to 3.8.1

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](https://github.com/sigstore/cosign-installer/compare/v3.7.0...v3.8.1)

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

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

.github/workflows/docker-publish.yml

@@ -39,7 +39,7 @@ jobs:
       # https://github.com/sigstore/cosign-installer
       - name: Install cosign
         if: github.event_name != 'pull_request'
-        uses: sigstore/cosign-installer@v3.7.0
+        uses: sigstore/cosign-installer@v3.8.1
         with:
           cosign-release: 'v2.4.1'