submodule: bump openthread from 71aed82 to f1e74a0 (#645)

Bumps [openthread](https://github.com/openthread/openthread) from `71aed82` to `f1e74a0`.
- [Commits](openthread/openthread@71aed82...f1e74a0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>