Bump body-parser from 2.2.0 to 2.2.1 in /backend

Bumps [body-parser](https://github.com/expressjs/body-parser) from 2.2.0 to 2.2.1.
- [Release notes](https://github.com/expressjs/body-parser/releases)
- [Changelog](https://github.com/expressjs/body-parser/blob/master/HISTORY.md)
- [Commits](expressjs/body-parser@v2.2.0...v2.2.1)

---
updated-dependencies:
- dependency-name: body-parser
  dependency-version: 2.2.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]