proxy: format imports with nightly rustfmt (#9414)

```shell
cargo +nightly fmt -p proxy -- -l --config imports_granularity=Module,group_imports=StdExternalCrate,reorder_imports=true
```

These rust-analyzer settings for VSCode should help retain this style:
```json
  "rust-analyzer.imports.group.enable": true,
  "rust-analyzer.imports.prefix": "crate",
  "rust-analyzer.imports.merge.glob": false,
  "rust-analyzer.imports.granularity.group": "module",
  "rust-analyzer.imports.granularity.enforce": true,
```

proxy/src/protocol2.rs

@@ -1,11 +1,9 @@
 //! Proxy Protocol V2 implementation
 
-use std::{
-    io,
-    net::SocketAddr,
-    pin::Pin,
-    task::{Context, Poll},
-};
+use std::io;
+use std::net::SocketAddr;
+use std::pin::Pin;
+use std::task::{Context, Poll};
 
 use bytes::BytesMut;
 use pin_project_lite::pin_project;