♻️(react) update token.ts to handles themes

Some components were using wrong design tokens and this was noticed
only when changing themes, like using hard-coded "white" instead of
"greyscale-000".

packages/react/src/components/Forms/Radio/tokens.ts

@@ -3,5 +3,5 @@ import { DefaultTokens } from "@openfun/cunningham-tokens";
 export const tokens = (defaults: DefaultTokens) => ({
   "border-color": defaults.theme.colors["greyscale-300"],
   "accent-color": defaults.theme.colors["success-600"],
-  "background-color": "white",
+  "background-color": defaults.theme.colors["greyscale-000"],
 });