Format buffer fails due to running in 2015

Hi,

I recently updated rust-mode and looking through the recent changes i see rustfmt is now invoked without the --edition flag.

I'm not getting errors when running rust-format-buffer.

I created a new project with edition = 2024 in Cargo.toml using $ cargo new proj.

Added an async function and ran rust-format-buffer and received the error:

error[E0670]: `async fn` is not permitted in Rust 2015
 --> main.rs:6:1
  |
6 | async fn give() -> String {
  | ^^^^^ to use `async fn`, switch to Rust 2018 or later
  |
  = help: pass `--edition 2024` to `rustc`
  = note: for more on editions, read https://doc.rust-lang.org/edition-guide

All configuration I have for rustmode is:

(use-package rust-mode
  :ensure t
  :init
  (setq rust-format-on-save t)
  :hook (rust-mode . eglot-ensure))

Is this the intended behavior?

Start at the rust-format-buffer entry point and the rustfmt invocation, then reproduce the failure with an async function in a project whose Cargo.toml declares edition 2024. Done means rust-format-buffer formats that buffer without interpreting it as Rust 2015.