upgrade dependency mio.

[longlongyang]

Fix #45

to fix CI error:

This vulnerability was originally reported in the Tokio issue tracker: [tokio-rs/tokio#6369](https://github.com/tokio-rs/tokio/issues/6369)  
      This vulnerability was fixed in: [tokio-rs/mio#1760](https://github.com/tokio-rs/mio/pull/1760)
      
      Thank you to [@rofoun](https://github.com/rofoun) and [@radekvit](https://github.com/radekvit) for discovering and reporting this issue.
    = Announcement: https://github.com/tokio-rs/mio/security/advisories/GHSA-r8w9-5wcg-vfj7
    = Solution: Upgrade to >=0.8.11 (try `cargo update -p mio`)
    = mio v0.8.8
      └── tokio v1.32.0
          ├── spdm-emu v0.1.0
          │   ├── spdm-requester-emu v0.1.0
          │   └── spdm-responder-emu v0.1.0
          ├── spdm-requester-emu v0.1.0 (*)
          └── spdm-responder-emu v0.1.0 (*)