submodule: bump openthread from `3243897` to `3ef8676` (#201)
submodule: bump openthread from `3243897` to `3ef8676` (#201)

Bumps [openthread](https://github.com/openthread/openthread) from `3243897` to `3ef8676`.
- [Commits](https://github.com/openthread/openthread/compare/3243897cd1af7788ecbcaf0326ed1f438bc9bb3c...3ef867602eef08a9bf3f60fb38db62a03e665cc0)

---
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-kw41z,openthread/ot-kw41z