submodule: bump openthread from `bef3f6e` to `9fb6b1b` (#212)
submodule: bump openthread from `bef3f6e` to `9fb6b1b` (#212)

Bumps [openthread](https://github.com/openthread/openthread) from `bef3f6e` to `9fb6b1b`.
- [Commits](https://github.com/openthread/openthread/compare/bef3f6e024394640ff8065a2862ebc3bc762de00...9fb6b1b1d014c1e7bcf525b893094de335c866a8)

---
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