Update cosign step in docker-publish.yml

.github/workflows/docker-publish.yml

@@ -4,6 +4,9 @@ name: Docker
 # They are provided by a third-party and are governed by
 # separate terms of service, privacy policy, and support
 # documentation.
+# 
+# Based on:
+# https://github.com/actions/starter-workflows/blob/main/ci/docker-publish.yml
 
 on:
   push:
@@ -116,10 +119,12 @@ jobs:
       - name: Sign the published Docker image
         if: ${{ github.event_name != 'pull_request' }}
         env:
-          COSIGN_EXPERIMENTAL: "true"
+          # https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-an-intermediate-environment-variable
+          TAGS: ${{ steps.meta.outputs.tags }}
+          DIGEST: ${{ steps.build-and-push.outputs.digest }}
         # This step uses the identity token to provision an ephemeral certificate
         # against the sigstore community Fulcio instance.
-        run: echo "${{ steps.meta.outputs.tags }}" | xargs -I {} cosign sign {}@${{ steps.build-and-push.outputs.digest }}
+        run: echo "${TAGS}" | xargs -I {} cosign sign --yes {}@${DIGEST}
 
       - name: Tag as latest
         uses: Actions-R-Us/actions-tagger@v2