Bump superdesk-core from 18c5362 to 43b4fbd in /client

Bumps [superdesk-core](https://github.com/superdesk/superdesk-client-core) from `18c5362` to `43b4fbd`.
- [Release notes](https://github.com/superdesk/superdesk-client-core/releases)
- [Commits](superdesk/superdesk-client-core@18c5362...43b4fbd)

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

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