Bump @testing-library/jest-dom from 6.6.4 to 6.9.1 in /site

Bumps [@testing-library/jest-dom](https://github.com/testing-library/jest-dom) from 6.6.4 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@v6.6.4...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
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

site/package-lock.json

@@ -49,7 +49,7 @@
     "pub": "rimraf ../docs && mv public ../docs"
   },
   "devDependencies": {
-    "@testing-library/jest-dom": "^6.6.4",
+    "@testing-library/jest-dom": "^6.9.1",
     "@testing-library/react": "^16.3.0",
     "babel-jest": "^29.7.0",
     "babel-preset-gatsby": "^3.13.2",