Enforce trybuild >= 1.0.108

Older versions produce slightly differently normalized output
when run against 1.90.0+ Rust compiler.

Author: dtolnay

Cargo.toml

@@ -27,7 +27,7 @@ futures = { version = "0.3", default-features = false }
 rustversion = "1.0.6"
 syn = { version = "2.0", features = ["full"] }
 thiserror = "2"
-trybuild = { version = "1.0.66", features = ["diff"] }
+trybuild = { version = "1.0.108", features = ["diff"] }
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]