fix unnecessary_underscores warning

Author: domesticmouse

deeplink_cookbook/lib/main.dart

@@ -8,12 +8,12 @@ final router = GoRouter(
   routes: [
     GoRoute(
       path: '/',
-      builder: (_, __) =>
+      builder: (_, _) =>
           Scaffold(appBar: AppBar(title: const Text('Home Screen'))),
       routes: [
         GoRoute(
           path: 'details',
-          builder: (_, __) =>
+          builder: (_, _) =>
               Scaffold(appBar: AppBar(title: const Text('Details Screen'))),
         ),
       ],