submodule: bump openthread from b2093f4 to b72d714 (#1182)

Bumps [openthread](https://github.com/openthread/openthread) from `b2093f4` to `b72d714`.
- [Commits](openthread/openthread@b2093f4...b72d714)

---
updated-dependencies:
- dependency-name: openthread
  dependency-version: b72d7144ee40e0550d6f507dff4be7a6b79c6100
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]