Bump newsroom-core from 257e156 to dc55efd in /client

Bumps [newsroom-core](https://github.com/superdesk/newsroom-core) from `257e156` to `dc55efd`.
- [Release notes](https://github.com/superdesk/newsroom-core/releases)
- [Commits](superdesk/newsroom-core@257e156...dc55efd)

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

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