submodule: bump openthread from `9272666` to `12a9ca1` (#111)
submodule: bump openthread from `9272666` to `12a9ca1` (#111)

Bumps [openthread](https://github.com/openthread/openthread) from `9272666` to `12a9ca1`.
- [Commits](https://github.com/openthread/openthread/compare/9272666541c463a1e04e4ab51b0a813e590af1d0...12a9ca19a7e51b3fc68ac3f0935348030d7c3098)

---
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-cc2538,openthread/ot-cc2538