chore: remove useless sinon dependency

Signed-off-by: Ferdinand Thiessen <[email protected]>

Author: susnux

build/frontend-legacy/package-lock.json

@@ -130,7 +130,6 @@
     "raw-loader": "^4.0.2",
     "regextras": "^0.8.0",
     "sass": "^1.93.3",
-    "sinon": "<= 21.0.1",
     "typescript": "^5.9.2",
     "vite": "^7.2.2",
     "vitest": "^3.2.4",