submodule: bump third_party/openthread/repo from 742b4e8 to 2ce3d3b (#1453)

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `742b4e8` to `2ce3d3b`.
- [Commits](openthread/openthread@742b4e8...2ce3d3b)

---
updated-dependencies:
- dependency-name: third_party/openthread/repo
  dependency-type: direct:production
...

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Author: dependabot[bot]