ci: Add pull request write permissions for cherry-pick workflow (#52927)

This was missing from the previous permissions changes.

Self-Review Checklist:

- [X] I've reviewed my own diff for quality, security, and reliability
- [ ] Unsafe blocks (if any) have justifying comments
- [ ] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [ ] Tests cover the new/changed behavior
- [X] Performance impact has been considered and is acceptable

Release Notes:

- N/A
5a74733aeeFinn Evers committed on 4/2/2026, 8:22:34 AM· committed by GitHubparentde28867
2 files changedLine totals unavailable