Update to code to Rust 1.67

src/tcp_relay_client/client_config.rs

@@ -93,7 +93,7 @@ fn load_pem_file(path: &Option<String>, name: &str) -> std::io::Result<Option<Ve
         None => None,
         Some(p) => Some(
             std::fs::read(p)
-                .map_err(|e| encpasulate_error(e, format!("Failed to load {}!", name)))?,
+                .map_err(|e| encpasulate_error(e, format!("Failed to load {name}!")))?,
         ),
     })
 }