Description：简要描述这次PR的内容
一个torch的bug:
nn.utils.rnn.pack_padded_sequence: RuntimeError: 'lengths' argument should be a 1D CPU int64 tensor, but got 1D cuda:0 Long tensor
详情查看:
https://github.com/pytorch/pytorch/issues/43227
Main reason: 做出这次修改的原因
兼容torch 1.70 GPU版本
Checklist 检查下面各项是否完成
Please feel free to remove inapplicable items for your PR.
[ ] The PR title starts with [$CATEGORY] (例如[bugfix]修复bug，[new]添加新功能，[test]修改测试，[rm]删除旧代码)
[ ] Changes are complete (i.e. I finished coding on this PR) 修改完成才提PR
[ ] All changes have test coverage 修改的部分顺利通过测试。对于fastnlp/fastnlp/的修改，测试代码必须提供在fastnlp/test/。
[ ] Code is well-documented 注释写好，API文档会从注释中抽取
[ ] To the my best knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change 修改导致例子或tutorial有变化，请找核心开发人员
Changes: 逐项描述修改的内容
添加了新模型；用于句子分类的CNN，来自Yoon Kim的Convolutional Neural Networks for Sentence Classification
Description：简要描述这次PR的内容 一个torch的bug: nn.utils.rnn.pack_padded_sequence: RuntimeError: 'lengths' argument should be a 1D CPU int64 tensor, but got 1D cuda:0 Long tensor 详情查看: https://github.com/pytorch/pytorch/issues/43227
Main reason: 做出这次修改的原因 兼容torch 1.70 GPU版本
Checklist 检查下面各项是否完成
Please feel free to remove inapplicable items for your PR.
Changes: 逐项描述修改的内容
Mention: 找人review你的PR
@修改过这个文件的人 @核心开发人员