chore: Remove testing-library

It wasn't used for any relevant tests, and svelte5 support is spotty.

package.json

@@ -29,8 +29,6 @@
     "@sveltejs/adapter-static": "3.0.8",
     "@sveltejs/kit": "2.20.0",
     "@sveltejs/vite-plugin-svelte": "^4.0.4",
-    "@testing-library/jest-dom": "^6.6.3",
-    "@testing-library/svelte": "^5.2.7",
     "@types/lodash-es": "^4.17.12",
     "@types/pako": "2.0.3",
     "@types/uuid": "9.0.8",