submodule: bump openthread from `1861291` to `b66d521` (#342)
submodule: bump openthread from `1861291` to `b66d521` (#342)

Bumps [openthread](https://github.com/openthread/openthread) from `1861291` to `b66d521`.
- [Commits](https://github.com/openthread/openthread/compare/1861291a621557ea03279c4eede3656462f3d88b...b66d521d1d08b9e8bec831a19ead00fec2a32ce9)

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

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

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
openthread/ot-kw41z,openthread/ot-kw41z