submodule: bump openthread from `dd16a05` to `51db0e5` (#102)
submodule: bump openthread from `dd16a05` to `51db0e5` (#102)

Bumps [openthread](https://github.com/openthread/openthread) from `dd16a05` to `51db0e5`.
- [Commits](https://github.com/openthread/openthread/compare/dd16a0587e276fcd9f0ee7ae97c3aa912c4bea61...51db0e54d74b6cf68f1b95e8f63874855d8e8a6d)

---
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-b91,openthread/ot-b91