fix: remove unused features in the syn crate

Author: frectonz

parenv-derive/Cargo.toml

@@ -11,6 +11,6 @@ readme = "../README.md"
 proc-macro = true
 
 [dependencies]
-syn = { version = "2.0", features = ["full", "extra-traits"] }
+syn = "2.0"
 quote = "1.0"
 proc-macro2 = "1.0.89"