Eliminate #[macro_use] from serde_derive

serde_derive/src/internals/ast.rs

@@ -2,6 +2,7 @@
 
 use crate::internals::{attr, check, Ctxt, Derive};
 use syn::punctuated::Punctuated;
+use syn::Token;
 
 /// A source data structure annotated with `#[derive(Serialize)]` and/or `#[derive(Deserialize)]`,
 /// parsed into an internal representation.