Update sigstore/cosign-installer action to v3.8.2

Author: renovate[bot]

.github/workflows/docker.yml

@@ -25,7 +25,7 @@ jobs:
       # https://github.com/sigstore/cosign-installer
       - name: Install cosign
         if: github.event_name != 'pull_request'
-        uses: sigstore/cosign-installer@v3.4.0
+        uses: sigstore/cosign-installer@v3.8.2
         with:
           cosign-release: "v2.2.3"