Remove unused mut detected by latest nightly
diff --git a/src/item.rs b/src/item.rs
index 9b5b7ea..118ed4e 100644
--- a/src/item.rs
+++ b/src/item.rs
@@ -1190,7 +1190,7 @@
             colon_token: input.parse()?,
             ty: match input.parse::<Token![...]>() {
                 Ok(dot3) => {
-                    let mut args = vec![
+                    let args = vec![
                         TokenTree::Punct(Punct::new('.', Spacing::Joint)),
                         TokenTree::Punct(Punct::new('.', Spacing::Joint)),
                         TokenTree::Punct(Punct::new('.', Spacing::Alone)),