Fix missing icon (#3652)

This PR fixes the missing icon for checkbox-empty.

### Change Type

- [x] `sdk` — Changes the tldraw SDK
- [x] `bugfix` — Bug fix

### Test Plan

1. Open the page menu
2. Create a new page
3. Should be no missing icon

packages/tldraw/src/lib/ui/components/primitives/Button/TldrawUiButtonCheck.tsx

@@ -5,7 +5,5 @@ export type TLUiButtonCheckProps = { checked: boolean }
 
 /** @public */
 export function TldrawUiButtonCheck({ checked }: TLUiButtonCheckProps) {
-	return (
-		<TldrawUiIcon icon={checked ? 'check' : 'checkbox-empty'} className="tlui-button__icon" small />
-	)
+	return <TldrawUiIcon icon={checked ? 'check' : 'none'} className="tlui-button__icon" small />
 }