build(deps): bump dompurify from 3.3.2 to 3.4.0 in /docs (#6381)

Bumps [dompurify](https://github.com/cure53/DOMPurify) from 3.3.2 to 3.4.0.
- [Release notes](https://github.com/cure53/DOMPurify/releases)
- [Commits](cure53/DOMPurify@3.3.2...3.4.0)

---
updated-dependencies:
- dependency-name: dompurify
  dependency-version: 3.4.0
  dependency-type: indirect
...

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Author: dependabot[bot]