【PaddlePaddle Hackathon 4】No.56 : add fp16 test and bf16 for trunc

[longranger2]

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Others

PR changes

APIs

Description

• add fp16 test and bf16 test for trunc

相关链接：
#51281

[paddle-bot]

你的PR提交成功，感谢你对开源项目的贡献!
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[paddle-bot]

❌ The PR is not created using PR's template. You can refer to this Demo.
Please use PR's template, it helps save our maintainers' time so that more developers get helped.

[paddle-bot]

很抱歉，经过我们的反复讨论，你的PR暂未达到合入标准，请阅读飞桨原生算子开发规范，你可以重新提交新的PR，我们先将此PR关闭，感谢你的贡献。
Sorry to inform you that through our discussion, your PR fails to meet the merging standard (Reference: Paddle Custom Operator Design Doc). You can also submit an new one. Thank you.

[ZzSean]

LGTM