Upgrade rustfmt edition to 2024

Author: eval-exec

Changelog.md

@@ -1,5 +1,6 @@
 # Unreleased
 
+- Update rustfmt's defaults to use 2024 edition ([#566](https://github.com/rust-lang/rust-mode/issues/509)).
 - Update rustfmt's defaults to use 2021 edition ([#554](https://github.com/rust-lang/rust-mode/issues/509)).
 - Introduce `rust-format-mode` for `rust-format-buffer` ([#556](https://github.com/rust-lang/rust-mode/pull/556)).
 

rust-rustfmt.el

@@ -33,7 +33,7 @@
   :type 'string
   :group 'rust-mode)
 
-(defcustom rust-rustfmt-switches '("--edition" "2021")
+(defcustom rust-rustfmt-switches '("--edition" "2024")
   "Arguments to pass when invoking the `rustfmt' executable."
   :type '(repeat string)
   :group 'rust-mode)