Update sigstore/cosign-installer digest to c56c2d3 (#365)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.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@789d2886c082e8fb7b9710810b73c3f0840573ed
+        uses: sigstore/cosign-installer@c56c2d3e59e4281cc41dea2217323ba5694b171e
         with:
           cosign-release: 'v1.9.0'