fix: File upload failed (#2398)

Author: shaohuzhang1

apps/dataset/serializers/file_serializers.py

@@ -57,7 +57,7 @@
 
 class FileSerializer(serializers.Serializer):
     file = UploadedFileField(required=True, error_messages=ErrMessage.image(_('file')))
-    meta = serializers.JSONField(required=False)
+    meta = serializers.JSONField(required=False, allow_null=True)
 
     def upload(self, with_valid=True):
         if with_valid: