Please add a security policy

The PSRT currently handles vulnerability reports for this repository. However, I presume that this is not the desired arrangement.

Please consider creating a .github/SECURITY.md file that documents the project’s security policy and vulnerability-reporting process. Even if the repository has not received vulnerability reports before, providing a clear reporting path ensures that any future reports reach the appropriate maintainers through your preferred process rather than being relayed by the PSRT.

Enabling private vulnerability reporting through GitHub Security Advisories would likely be the most convenient option for this project. Please feel free to ping me with any questions or if you would like a review. :-)

Alternatively, if you would prefer to continue using the current PSRT-managed process, please let us know. We are making minor changes to that process, as described in https://github.com/python/psrt-ghsa-bot/issues/60.

从创建 .github/SECURITY.md 的请求开始，审查仓库当前由 PSRT 管理的漏洞报告安排，包括链接的流程 issue。完成的标准是：该文件记录一条经维护者同意的明确报告路径，或者明确确认仓库将继续采用 PSRT 流程。