Merge pull request #32 from solid-software/subscription-pause

Add subscription.pause_collection field

Author: yurii-prykhodko-solid

lib/messages.dart

@@ -1,6 +1,7 @@
 import 'package:json_annotation/json_annotation.dart';
 import 'package:stripe/src/messages/converters.dart';
 import 'package:stripe/src/messages/enums.dart';
+import 'package:stripe/src/messages/enums/pause_collection_behavior.dart';
 
 export 'package:stripe/src/messages/enums.dart';
 
@@ -19,6 +20,7 @@ part 'src/messages/discount.dart';
 part 'src/messages/event.dart';
 part 'src/messages/invoice.dart';
 part 'src/messages/payment_intent.dart';
+part 'src/messages/pause_collection.dart';
 part 'src/messages/payment_method.dart';
 part 'src/messages/portal_session.dart';
 part 'src/messages/price.dart';