infra: update stable Rust toolchain to 1.88.0

Updating the toolchain required a fix to steam-track as the
`uninlined_format_args` lint was moved from the `pedantic` group to
the `style` group of lints, see
rust-lang/rust-clippy#14160.

As the `clippy::all` group does not include the pedantic group, warnings
were emitted for the generated Cap'n Proto code. To disable all warnings
currently raised both clippy allow attributes are now required.

Author: samchesney

rust-toolchain.toml

@@ -1,5 +1,5 @@
 # Copyright (c) 2025 Graphcore Ltd. All rights reserved.
 
 [toolchain]
-channel = "1.87.0"
+channel = "1.88.0"
 profile = "default"

steam-track/src/lib.rs

@@ -285,6 +285,7 @@ macro_rules! error {
 pub mod steam_track_capnp {
     // No need to emit warnings for auto-generated Cap'n Proto code
     #![allow(missing_docs)]
+    #![allow(clippy::all)]
     #![allow(clippy::pedantic)]
 
     include!(concat!(env!("OUT_DIR"), "/steam_track_capnp.rs"));