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 @@ serde = { version = "1.0.194", features = ["derive"] }
 serde_bytes = "0.11.10"
 serde_derive = "1.0.166"
 serde_stacker = "0.1.8"
-trybuild = { version = "1.0.81", features = ["diff"] }
+trybuild = { version = "1.0.108", features = ["diff"] }
 
 [package.metadata.docs.rs]
 features = ["preserve_order", "raw_value", "unbounded_depth"]