Bump superdesk-planning from cebd5db to afcb468 in /client

Bumps [superdesk-planning](https://github.com/superdesk/superdesk-planning) from `cebd5db` to `afcb468`.
- [Release notes](https://github.com/superdesk/superdesk-planning/releases)
- [Commits](superdesk/superdesk-planning@cebd5db...afcb468)

---
updated-dependencies:
- dependency-name: superdesk-planning
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>