persist-client: ignore warning about #[track_caller]

`#[track_caller]` has no effect on async functions currently, and the
compiler warns about that. However, fixing this is in progress ([0]).
Rather than removing the annotations from async functions, we instead
ignore the compiler warning, so we don't forget to add the annotations
again once [0] is implemented.

[0]: rust-lang/rust#87417

Author: teskje

src/persist-client/src/lib.rs

@@ -78,6 +78,10 @@
 
 #![doc = include_str!("../README.md")]
 #![warn(missing_docs, missing_debug_implementations)]
+// #[track_caller] is currently a no-op on async functions, but that hopefully won't be the case
+// forever. So we already annotate those functions now and ignore the compiler warning until
+// https://github.com/rust-lang/rust/issues/87417 pans out.
+#![allow(ungated_async_fn_track_caller)]
 
 use std::fmt::Debug;
 use std::marker::PhantomData;