aya: appease nightly lint

```
error: lint `unused_tuple_struct_fields` has been renamed to `dead_code`
  --> aya/src/lib.rs:74:5
   |
74 |     unused_tuple_struct_fields,
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `dead_code`
   |
   = note: `-D renamed-and-removed-lints` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(renamed_and_removed_lints)]`
```

See rust-lang/rust@9fcf9c141068984ffcbb4cb00c.

aya/src/lib.rs

@@ -71,7 +71,6 @@
     unused_macro_rules,
     unused_qualifications,
     //unused_results,
-    unused_tuple_struct_fields,
 )]
 #![allow(clippy::missing_safety_doc, clippy::len_without_is_empty)]
 #![cfg_attr(