加入类型转换逻辑，防止解码失败

db/task_db.py

@@ -179,11 +179,16 @@ class TaskDBOperator(BaseDBOperator):
             values = []
             # 需要序列化的字段
             json_fields = ['groups', 'content_miniprogram', 'preview_recipients', 'content_link', 'weekly_days']
+            # datetime字段
+            datetime_fields = ['recurring_end', 'recurring_time', 'schedule_time']
             
             for key, value in updates.items():
                 # 跳过空值字段
                 if value is None or (isinstance(value, list) and len(value) == 0):
                     continue
+                # 跳过datetime字段的空字符串
+                if key in datetime_fields and value == '':
+                    continue
                     
                 fields.append(f"{key} = %s")
                 # 如果是需要序列化的字段，且值不是字符串类型，则进行序列化