submodule: bump openthread from 4e3483c to d0fbfb8 (#851)

Bumps [openthread](https://github.com/openthread/openthread) from `4e3483c` to `d0fbfb8`.
- [Commits](openthread/openthread@4e3483c...d0fbfb8)

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

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