Bump anstream from 0.6.4 to 0.6.20 in /loadgen/kitchen-sink-gen

Bumps [anstream](https://github.com/rust-cli/anstyle) from 0.6.4 to 0.6.20.
- [Commits](rust-cli/anstyle@anstream-v0.6.4...anstream-v0.6.20)

---
updated-dependencies:
- dependency-name: anstream
  dependency-version: 0.6.20
  dependency-type: indirect
...

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Author: dependabot[bot]