Bump newsroom-core from ebc274d to c31b2b9 in /client

Bumps [newsroom-core](https://github.com/superdesk/newsroom-core) from `ebc274d` to `c31b2b9`.
- [Release notes](https://github.com/superdesk/newsroom-core/releases)
- [Commits](superdesk/newsroom-core@ebc274d...c31b2b9)

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

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