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/mcp-server/src/codex_tool_config.rs

@@ -4,8 +4,8 @@ use std::path::PathBuf;
 
 use mcp_types::Tool;
 use mcp_types::ToolInputSchema;
-use schemars::r#gen::SchemaSettings;
 use schemars::JsonSchema;
+use schemars::r#gen::SchemaSettings;
 use serde::Deserialize;
 
 use codex_core::protocol::AskForApproval;