Merge pull request #8 from tateru/fix-ci2

CI: avoid cosign prompting for user input

.github/workflows/docker-publish.yml

@@ -89,5 +89,5 @@ jobs:
         if: ${{ github.event_name != 'pull_request' }}
         # This step uses the identity token to provision an ephemeral certificate
         # against the sigstore community Fulcio instance.
-        run: echo "${{ steps.meta.outputs.tags }}" | xargs -I {} cosign sign {}@${{ steps.build-and-push.outputs.digest }}
+        run: echo "${{ steps.meta.outputs.tags }}" | xargs -I {} cosign sign --yes {}@${{ steps.build-and-push.outputs.digest }}