Bump js-yaml from 3.14.1 to 3.14.2 in /backend

Bumps [js-yaml](https://github.com/nodeca/js-yaml) from 3.14.1 to 3.14.2.
- [Changelog](https://github.com/nodeca/js-yaml/blob/master/CHANGELOG.md)
- [Commits](nodeca/js-yaml@3.14.1...3.14.2)

---
updated-dependencies:
- dependency-name: js-yaml
  dependency-version: 3.14.2
  dependency-type: indirect
...

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Author: dependabot[bot]