Upgrading pigeon version to ^8.0.0

Created a single commit for the pigeon upgrade so it is easier to read the second commit
where changes to `message.dart` will be done

Author: gabrielgarciagava

packages/video_player/video_player_avfoundation/ios/Classes/messages.g.h

@@ -1,9 +1,11 @@
 // Copyright 2013 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-// Autogenerated from Pigeon (v2.0.1), do not edit directly.
+// Autogenerated from Pigeon (v8.0.0), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
+
 #import <Foundation/Foundation.h>
+
 @protocol FlutterBinaryMessenger;
 @protocol FlutterMessageCodec;
 @class FlutterError;