Fix Vue 3 setup callback function typing

[xieyuheng]

Related JavaScript code: https://github.com/inertiajs/inertia/blob/master/packages/inertia-vue3/src/createInertiaApp.js#L15

A stackoverflow question about this issue: https://stackoverflow.com/questions/69583649/error-on-app-variable-in-a-inertia-js-laravel-typescript-vue-3-applicati