build(deps-dev): bump happy-dom from 19.0.2 to 20.8.9

Bumps [happy-dom](https://github.com/capricorn86/happy-dom) from 19.0.2 to 20.8.9.
- [Release notes](https://github.com/capricorn86/happy-dom/releases)
- [Commits](capricorn86/happy-dom@v19.0.2...v20.8.9)

---
updated-dependencies:
- dependency-name: happy-dom
  dependency-version: 20.8.9
  dependency-type: direct:development
...

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

Author: dependabot[bot]

package.json

@@ -6,7 +6,7 @@
     "eslint": "^9.35.0",
     "eslint-config-prettier": "^10.1.8",
     "eslint-plugin-prettier": "^5.5.4",
-    "happy-dom": "^19.0.2",
+    "happy-dom": "^20.8.9",
     "markdown-it-container": "^4.0.0",
     "prettier": "^3.6.2",
     "vite-plugin-vuetify": "^2.1.2",