Update sigstore/cosign-installer action to v3.9.1

Author: renovate[bot]

.github/workflows/docker-image.yaml

@@ -25,7 +25,7 @@ jobs:
 
       - name: Install cosign
         if: github.event_name != 'pull_request'
-        uses: sigstore/cosign-installer@v3.8.1
+        uses: sigstore/cosign-installer@v3.9.1
 
       - name: Docker meta
         id: meta