Tokio 1.0 (#1813)

Co-authored-by: Rob Ede <robjtede@icloud.com>

src/types/json.rs

@@ -367,7 +367,7 @@ where
         let json = if let Ok(Some(mime)) = req.mime_type() {
             mime.subtype() == mime::JSON
                 || mime.suffix() == Some(mime::JSON)
-                || ctype.as_ref().map_or(false, |predicate| predicate(mime))
+                || ctype.map_or(false, |predicate| predicate(mime))
         } else {
             false
         };