Merge pull request #15 from cyso/renovate/sigstore-cosign-installer-2.x

Update sigstore/cosign-installer action to v2.8.1

Author: jochbru

.github/workflows/docker-publish.yml

@@ -41,7 +41,7 @@ jobs:
       # https://github.com/sigstore/cosign-installer
       - name: Install cosign
         if: github.event_name != 'pull_request'
-        uses: sigstore/cosign-installer@db0f512372e476bcdfc58b21303b1407a4313ccc # v2.6.0
+        uses: sigstore/cosign-installer@c85d0e205a72a294fe064f618a87dbac13084086 # v2.8.1
         with:
           cosign-release: 'v1.13.1'