use cosign v2.6.1

Author: mickmis

.github/workflows/image-publish.yml

@@ -29,6 +29,8 @@ jobs:
     steps:
       - name: Install Cosign
         uses: sigstore/cosign-installer@faadad0cce49287aee09b3a48701e75088a2c6ad  # v4.0.0
+        with:
+          cosign-release: 'v2.6.1'
       - name: Job information
         run: |
           echo "Job information"