submodule: bump openthread from `b69aac4` to `55af6ce` (#219)
submodule: bump openthread from `b69aac4` to `55af6ce` (#219)

Bumps [openthread](https://github.com/openthread/openthread) from `b69aac4` to `55af6ce`.
- [Commits](https://github.com/openthread/openthread/compare/b69aac4aa85b410dbe54950741df39b306458ba2...55af6ce2c852b870f7477a2508861830d2a4184e)

---
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-efr32,openthread/ot-efr32,openthread/ot-efr32