submodule: bump openthread from `9a2d84a` to `d2f18d5` (#262)
submodule: bump openthread from `9a2d84a` to `d2f18d5` (#262)

Bumps [openthread](https://github.com/openthread/openthread) from `9a2d84a` to `d2f18d5`.
- [Commits](https://github.com/openthread/openthread/compare/9a2d84a4b78413e20f269df96a855e573e04a616...d2f18d5ebc194e5086f2041218dbb160824ebb69)

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

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
openthread/ot-samr21,openthread/ot-samr21