submodule: bump openthread from 42ccf28 to 383d0d2 (openthread#855)

Bumps [openthread](https://github.com/openthread/openthread) from `42ccf28` to `383d0d2`.
- [Commits](openthread/openthread@42ccf28...383d0d2)

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

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