submodule: bump third_party/openthread/repo from `697c5e5` to `43c66a3` (#1568)
submodule: bump third_party/openthread/repo from `697c5e5` to `43c66a3` (#1568)

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `697c5e5` to `43c66a3`.
- [Commits](https://github.com/openthread/openthread/compare/697c5e53a243f94df0d9249da8bb4e73a141cd27...43c66a3d5f73857b95ef5448cade3442d4449277)

---
updated-dependencies:
- dependency-name: third_party/openthread/repo
  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-br-posix,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/ot-br-posix,openthread/ot-br-posix,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter