fix: Knowledge export error

Author: zhanweizhang7

apps/knowledge/serializers/knowledge.py

@@ -635,6 +635,8 @@ def _get_knowledge_workbook(data_dict: dict, document_dict: dict, doc_tag_map: d
                     para_active = para_active_list[row_idx] if row_idx < len(para_active_list) else '1'
                     # None 转为 ''
                     row = [col if col is not None else '' for col in row]
+                    # 补齐到3列
+                    row = (row + ['','',''])[:3]
                     if row_idx == 0:
                         data.append(
                             [*row, tags_str, hit_method, similarity, is_active, para_active, doc_type, doc_meta])