tests: Ignore elided_named_lifetimes lint

```
error: elided lifetime has a name
  --> tests/elisions.rs:23:21
   |
23 |     #[stream(item = &i32)]
   |     ----------------^-----
   |     |               |
   |     |               this elided lifetime gets resolved as `'_async0`
   |     lifetime `'_async0` declared here
   |
   = note: `-D elided-named-lifetimes` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(elided_named_lifetimes)]`

error: elided lifetime has a name
  --> tests/elisions.rs:29:17
   |
29 | #[stream(item = &i32)]
   | ----------------^-----
   | |               |
   | |               this elided lifetime gets resolved as `'_async0`
   | lifetime `'_async0` declared here
```

tests/elisions.rs

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: Apache-2.0 OR MIT
 
-#![allow(dead_code, clippy::needless_pass_by_value)]
+#![allow(dead_code, unknown_lints, elided_named_lifetimes, clippy::needless_pass_by_value)]
 #![feature(coroutines)]
 
 use futures_async_stream::stream;