* Fixes non-binding let on a future (ip-echo-server)
```
warning: non-binding `let` on a future
--> net-utils/src/ip_echo_server.rs:133:13
|
133 | let _ = tcp_stream.shutdown();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: consider awaiting the future or dropping explicitly with `std::mem::drop`
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_future
= note: `-D clippy::let-underscore-future` implied by `-D warnings`
```
* pr: remove let
* pr: ?