Raise sponsors PRs as a draft

See
https://github.com/peter-evans/create-pull-request/blob/main/docs/concepts-guidelines.md#workarounds-to-trigger-further-workflow-runs

.github/workflows/sponsors.yml

@@ -26,3 +26,4 @@ jobs:
           author: "github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>"
           labels: "ignore-for-release"
           delete-branch: true
+          draft: always-true