dockerfile: update rust version

Dockerfile

@@ -1,4 +1,4 @@
-FROM rust:1.57-bullseye as builder
+FROM rust:1.69-bullseye as builder
 
 RUN apt-get update && \
     apt-get install -y libssl-dev pkg-config

src/fw.rs

@@ -1,4 +1,5 @@
 use std::collections::HashSet;
+use std::sync::Arc;
 
 use anyhow::{Context, Result};
 use iptables;