docker-publish.yml: Add --yes to "cosign sign" command

Fixes error where interactive prompt does not work in GitHub Actions CI.

See sigstore/cosign-installer#110

Author: anthonyfok

.github/workflows/docker-publish.yml

@@ -105,4 +105,4 @@ jobs:
           COSIGN_EXPERIMENTAL: "true"
         # 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 }}