Ensure closing bracket when adding serializers

Author: epou

modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/built_value/serializers.mustache

@@ -38,8 +38,8 @@ Serializers serializers = (_$serializers.toBuilder(){{#builtValueSerializers}}
       ..add(const OffsetDateSerializer())
       ..add(const OffsetDateTimeSerializer()){{/useDateLibTimeMachine}}{{#useDateLibCore}}
       ..add(const DateSerializer())
-      ..add(Iso8601DateTimeSerializer())){{/useDateLibCore}}
-    .build();
+      ..add(Iso8601DateTimeSerializer()){{/useDateLibCore}}
+    ).build();
 
 Serializers standardSerializers =
     (serializers.toBuilder()..addPlugin(StandardJsonPlugin())).build();