Bump qs from 5.2.0 to 6.7.0 in /src/samples/conference (#438)

Bumps [qs](https://github.com/ljharb/qs) from 5.2.0 to 6.7.0.
- [Release notes](https://github.com/ljharb/qs/releases)
- [Changelog](https://github.com/ljharb/qs/blob/master/CHANGELOG.md)
- [Commits](ljharb/qs@v5.2.0...v6.7.0)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]