Update cargo to 2024 edition (#842)

Some effects of this change:
- New formatting changes across many files. No functionality changes
should occur from that.
- Calls to `set_env` are considered unsafe, since this only happens in
tests we wrap them in `unsafe` blocks

codex-rs/tui/src/scroll_event_helper.rs

@@ -1,12 +1,12 @@
+use std::sync::Arc;
 use std::sync::atomic::AtomicBool;
 use std::sync::atomic::AtomicI32;
 use std::sync::atomic::Ordering;
 use std::sync::mpsc::Sender;
-use std::sync::Arc;
 
 use tokio::runtime::Handle;
-use tokio::time::sleep;
 use tokio::time::Duration;
+use tokio::time::sleep;
 
 use crate::app_event::AppEvent;