submodule: bump openthread from 5be432e to 9b0d3db

Bumps [openthread](https://github.com/openthread/openthread) from `5be432e` to `9b0d3db`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@5be432e...9b0d3db)

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

Signed-off-by: dependabot[bot] <[email protected]>