Bumps [serde_yaml](https://github.com/dtolnay/serde-yaml) from 0.8.20 to 0.8.21.
- [Release notes](https://github.com/dtolnay/serde-yaml/releases)
- [Commits](dtolnay/serde-yaml@0.8.20...0.8.21)

---
updated-dependencies:
- dependency-name: serde_yaml
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

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