Bump @mitre/saf from 1.4.20 to 1.4.21

Bumps [@mitre/saf](https://github.com/mitre/saf) from 1.4.20 to 1.4.21.
- [Release notes](https://github.com/mitre/saf/releases)
- [Changelog](https://github.com/mitre/saf/blob/main/release-prep.ps1)
- [Commits](mitre/saf@1.4.20...1.4.21)

---
updated-dependencies:
- dependency-name: "@mitre/saf"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]