chore(deps-dev): bump happy-dom in /apps/flexfields

Bumps [happy-dom](https://github.com/capricorn86/happy-dom) from 14.12.3 to 15.7.3.
- [Release notes](https://github.com/capricorn86/happy-dom/releases)
- [Commits](capricorn86/happy-dom@v14.12.3...v15.7.3)

---
updated-dependencies:
- dependency-name: happy-dom
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

apps/flexfields/package.json

@@ -53,7 +53,7 @@
     "@typescript-eslint/parser": "^8.5.0",
     "@vitejs/plugin-react": "^4.3.1",
     "@vitest/browser": "^2.0.5",
-    "happy-dom": "^14.12.3",
+    "happy-dom": "^15.7.3",
     "playwright": "^1.47.0",
     "typescript": "5.4.3",
     "vite": "^5.4.3",