submodule: bump openthread from 459a4cb to f67ca58 (#1156)

Bumps [openthread](https://github.com/openthread/openthread) from `459a4cb` to `f67ca58`.
- [Commits](openthread/openthread@459a4cb...f67ca58)

---
updated-dependencies:
- dependency-name: openthread
  dependency-version: f67ca58c824e4e11e480e80020371612d2f5cb15
  dependency-type: direct:production
...

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