Bump github.com/containerd/containerd from 1.5.2 to 1.6.26 in /test/src

Bumps [github.com/containerd/containerd](https://github.com/containerd/containerd) from 1.5.2 to 1.6.26.
- [Release notes](https://github.com/containerd/containerd/releases)
- [Changelog](https://github.com/containerd/containerd/blob/main/RELEASES.md)
- [Commits](containerd/containerd@v1.5.2...v1.6.26)

---
updated-dependencies:
- dependency-name: github.com/containerd/containerd
  dependency-type: indirect
...

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