FormData doesn't collect the submitted button value

**Problem**
The formdata passed by onsubmit doesn't include the submitted button.

**Steps To Reproduce**

Steps to reproduce the behavior:
```
rsx! {
form {
onsubmit: |event| dioxus_logger::tracing::debug!(?event),
button { name: "btn_test", r#type: "submit", value: "submit", "Submit" }
}
}
```

**Expected behavior**

According to this [MDN doc](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button#value), the submitted button value should be included in the form data.

**Screenshots**

**Environment:**
- Dioxus version: `0.5.1`
- Rust version: `rustc 1.83.0-nightly (f79a912d9 2024-09-18)`
- OS info:
- App platform: web