Bump qs and body-parser in /src/samples/conference (#567)

Bumps [qs](https://github.com/ljharb/qs) to 6.11.0 and updates ancestor dependency [body-parser](https://github.com/expressjs/body-parser). These dependencies need to be updated together.


Updates `qs` from 6.7.0 to 6.11.0
- [Release notes](https://github.com/ljharb/qs/releases)
- [Changelog](https://github.com/ljharb/qs/blob/main/CHANGELOG.md)
- [Commits](ljharb/qs@v6.7.0...v6.11.0)

Updates `body-parser` from 1.19.0 to 1.20.1
- [Release notes](https://github.com/expressjs/body-parser/releases)
- [Changelog](https://github.com/expressjs/body-parser/blob/master/HISTORY.md)
- [Commits](expressjs/body-parser@1.19.0...1.20.1)

---
updated-dependencies:
- dependency-name: qs
  dependency-type: indirect
- dependency-name: body-parser
  dependency-type: direct:production
...

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