Bump dompurify from 3.4.5 to 3.4.12 in /docs

Bumps [dompurify](https://github.com/cure53/DOMPurify) from 3.4.5 to 3.4.12.
- [Release notes](https://github.com/cure53/DOMPurify/releases)
- [Commits](cure53/DOMPurify@3.4.5...3.4.12)

---
updated-dependencies:
- dependency-name: dompurify
  dependency-version: 3.4.12
  dependency-type: indirect
...

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Author: dependabot[bot]