Motivation

在PT2.0及以后的版本中，torch._six弃用了。

Modification

修改 “from torch._six import inf” 为从math进行导入。

Self-test

已验证

Checklist

Before PR:

• The new code needs to comply with the Clean Code specification.
• The PR content is self-checked, and the expression can be clear and the writing standardized

After PR:

• CLA has been signed and all committers have signed the CLA in this PR.
• The ci-pipeline is passed, Code Check is passed.