Bump dompurify from 3.1.1 to 3.1.6 in /ui/ui-docs (#5181)

Bumps [dompurify](https://github.com/cure53/DOMPurify) from 3.1.1 to 3.1.6.
- [Release notes](https://github.com/cure53/DOMPurify/releases)
- [Commits](cure53/DOMPurify@3.1.1...3.1.6)

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

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