Update dev-dependencies to thiserror v2

Author: dtolnay

Cargo.toml

@@ -26,7 +26,7 @@ backtrace = { version = "0.3.51", optional = true }
 futures = { version = "0.3", default-features = false }
 rustversion = "1.0.6"
 syn = { version = "2.0", features = ["full"] }
-thiserror = "1.0.45"
+thiserror = "2"
 trybuild = { version = "1.0.66", features = ["diff"] }
 
 [lib]