Enforce trybuild >= 1.0.108

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

Author: dtolnay

Cargo.toml

@@ -34,7 +34,7 @@ thiserror-impl = { version = "=2.0.16", path = "impl" }
 anyhow = "1.0.73"
 ref-cast = "1.0.18"
 rustversion = "1.0.13"
-trybuild = { version = "1.0.81", features = ["diff"] }
+trybuild = { version = "1.0.108", features = ["diff"] }
 
 [workspace]
 members = ["impl", "tests/no-std"]