build(deps): bump zerocopy in /userspace/drivers/virtiod

Bumps [zerocopy](https://github.com/google/zerocopy) from 0.6.4 to 0.6.6.
- [Release notes](https://github.com/google/zerocopy/releases)
- [Changelog](https://github.com/google/zerocopy/blob/main/CHANGELOG.md)
- [Commits](google/zerocopy@v0.6.4...v0.6.6)

---
updated-dependencies:
- dependency-name: zerocopy
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>