`single_use_lifetimes` warns when deriving a struct

When compiling 

```rust {.line-numbers}
#![warn(single_use_lifetimes)]

#[derive(Debug)]
struct Foo<'a> {
    bar: &'a u32,
}
```
this warning is generated:
```
warning: lifetime parameter `'a` only used once
 --> src/lib.rs:5:12
  |
5 | struct Foo<'a> {
  |            ^^
  |
```

I think, `#[automatically_derived]` in the `Debug` derive does not consider this lint.