Bump @testing-library/jest-dom in /src/Elastic.Documentation.Site (#2077)

Bumps [@testing-library/jest-dom](https://github.com/testing-library/jest-dom) from 6.8.0 to 6.9.1.
- [Release notes](https://github.com/testing-library/jest-dom/releases)
- [Changelog](https://github.com/testing-library/jest-dom/blob/main/CHANGELOG.md)
- [Commits](testing-library/jest-dom@v6.8.0...v6.9.1)

---
updated-dependencies:
- dependency-name: "@testing-library/jest-dom"
  dependency-version: 6.9.1
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

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

@@ -51,7 +51,7 @@
     "@eslint/js": "9.36.0",
     "@parcel/reporter-bundle-analyzer": "2.16.0",
     "@tailwindcss/postcss": "4.1.14",
-    "@testing-library/jest-dom": "6.8.0",
+    "@testing-library/jest-dom": "6.9.1",
     "@testing-library/react": "16.3.0",
     "@testing-library/user-event": "14.6.1",
     "@trivago/prettier-plugin-sort-imports": "5.2.2",