Update sigstore/cosign-installer digest to b6ee8f8

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -65,7 +65,7 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
       - name: Install cosign
-        uses: sigstore/cosign-installer@162dfdf7b9ab8be88c95b4fc982792c4c273e27a
+        uses: sigstore/cosign-installer@b6ee8f83b9a8b8ef7f46b5a8ff326f488b386693
         with:
           cosign-release: 'v1.13.1'
       # for multi arch container builds