build(deps-dev): bump moto from 5.1.20 to 5.1.21

Bumps [moto](https://github.com/getmoto/moto) from 5.1.20 to 5.1.21.
- [Release notes](https://github.com/getmoto/moto/releases)
- [Changelog](https://github.com/getmoto/moto/blob/master/CHANGELOG.md)
- [Commits](getmoto/moto@5.1.20...5.1.21)

---
updated-dependencies:
- dependency-name: moto
  dependency-version: 5.1.21
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]