Bump knex and unleash-server

Bumps [knex](https://github.com/knex/knex) to 2.4.2 and updates ancestor dependency [unleash-server](https://github.com/unleash/unleash). These dependencies need to be updated together.


Updates `knex` from 0.21.21 to 2.4.2
- [Release notes](https://github.com/knex/knex/releases)
- [Changelog](https://github.com/knex/knex/blob/master/CHANGELOG.md)
- [Commits](https://github.com/knex/knex/commits)

Updates `unleash-server` from 3.17.6 to 4.21.1
- [Release notes](https://github.com/unleash/unleash/releases)
- [Changelog](https://github.com/Unleash/unleash/blob/main/CHANGELOG.md)
- [Commits](Unleash/unleash@v3.17.6...v4.21.1)

---
updated-dependencies:
- dependency-name: knex
  dependency-type: indirect
- dependency-name: unleash-server
  dependency-type: direct:production
...

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