submodule: bump openthread from 4a9fb06 to 5058500

Bumps [openthread](https://github.com/openthread/openthread) from `4a9fb06` to `5058500`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@4a9fb06...5058500)

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

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