Bump dompurify from 3.3.2 to 3.4.0 in /src/Elastic.Documentation.Site (#3119)

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: direct:production
...

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Author: dependabot[bot]

src/Elastic.Documentation.Site/package-lock.json

@@ -120,7 +120,7 @@
     "@tanstack/react-query": "^5.90.6",
     "@uidotdev/usehooks": "2.4.1",
     "@theletterf/beautiful-mermaid": "0.1.5",
-    "dompurify": "3.3.2",
+    "dompurify": "3.4.0",
     "highlight.js": "11.11.1",
     "htmx-ext-head-support": "2.0.5",
     "htmx-ext-preload": "2.1.2",