submodule: bump openthread from 79a3a26 to d94c4e0 (#567)

Bumps [openthread](https://github.com/openthread/openthread) from `79a3a26` to `d94c4e0`.
- [Commits](openthread/openthread@79a3a26...d94c4e0)

---
updated-dependencies:
- dependency-name: openthread
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>