chore: remove redundant pattern (#956)

Author: Eric Szentiványi

typify-impl/src/util.rs

@@ -783,7 +783,6 @@ pub(crate) fn sanitize(input: &str, case: Case) -> String {
 
     // If every case was special then none of them would be.
     let out = match input {
-        "async" => "async_".to_string(), // TODO syn should handle this case...
         "+1" => "plus1".to_string(),
         "-1" => "minus1".to_string(),
         _ => to_case(&input.replace("'", "").replace(|c| !is_xid_continue(c), "-")),