set style edition to 2024

Summary:
Remove warning when running `rustfmt`:
```
Warning: the `version` option is deprecated. Use `style_edition` instead.
```
by replacing `version` with `style_edition` and setting its value to `2024` ([docs](https://rust-lang.github.io/rustfmt/?version=v1.8.0&search=#style_edition))

Reviewed By: dtolnay

Differential Revision: D73054142

fbshipit-source-id: bd316f8eecf1d1eaba75319f7ab2a67cc06fabbd

Author: diliop

.rustfmt.toml

@@ -5,5 +5,5 @@ format_code_in_doc_comments = true
 group_imports = "StdExternalCrate"
 imports_granularity = "Item"
 merge_derives = false
+style_edition = "2024"
 use_field_init_shorthand = true
-version = "Two"