chore: fix lint

Author: Zekfad

lib/src/fetch_options/fetch_options.dart

@@ -63,6 +63,7 @@ class FetchOptions {
     String? integrity,
     bool? keepalive,
     AbortSignal? signal,
+    // ignore: unused_element
     String? duplex,
   });
 

lib/src/request_options/request_options.dart

@@ -61,6 +61,7 @@ class RequestOptions {
     String? integrity,
     bool? keepalive,
     AbortSignal? signal,
+    // ignore: unused_element
     String? duplex,
   });