Simplify Unsplash response handling (#1077)

desktop_photo_search/material/lib/src/unsplash/unsplash.dart

@@ -72,12 +72,7 @@ class Unsplash {
       throw UnsplashException(apiError.errors!.join(', '));
     }
 
-    return SearchPhotosResponse.fromJson(
-      // Per Response#body, if the Content-Type header is unknown, bodyBytes
-      // is interpreted as latin1. Unsplash returns utf8, but with no encoding
-      // specified in the Content-Type, so we must do it ourselves.
-      utf8.decode(response.bodyBytes),
-    );
+    return SearchPhotosResponse.fromJson(json.encode(body));
   }
 
   Future<Uint8List> download(Photo photo) async {