Fastify-multipart filebody loops itself

## 💬 Question here

Is it on purpose that when you get a file from a multipart file body that it creates a loop in itself?

```js
import {fastify as f} from "fastify"
import multipart from "@fastify/multipart"

const fastify = f()

fastify.register(multipart)

fastify.post('/', async function (req, reply) {
const data = await req.file()

console.log(data)

reply.send()
})

fastify.listen({ port: 3000 }, err => {
if (err) throw err
console.log(`server listening on ${fastify.server.address().port}`)
})
````


## Your Environment

- *node version*: 16.10
- *fastify version*: 4.3.0 | @fastify/multipart: 7.1.0
- *os*: Any