Update sigstore/cosign-installer action to v3.8.0

Author: renovate[bot]

.github/workflows/docker-publish.yml

@@ -40,7 +40,7 @@ jobs:
       # https://github.com/sigstore/cosign-installer
       - name: Install cosign
         if: github.event_name != 'pull_request'
-        uses: sigstore/cosign-installer@4959ce089c160fddf62f7b42464195ba1a56d382 # v3.6.0
+        uses: sigstore/cosign-installer@c56c2d3e59e4281cc41dea2217323ba5694b171e # v3.8.0
         with:
           cosign-release: 'v2.2.4'