submodule: bump openthread from `d8ad60f` to `6fa60be` (#128)
submodule: bump openthread from `d8ad60f` to `6fa60be` (#128)

Bumps [openthread](https://github.com/openthread/openthread) from `d8ad60f` to `6fa60be`.
- [Commits](https://github.com/openthread/openthread/compare/d8ad60ff6db7a3af92674ce508c5dfc31165d047...6fa60be75ccaebadc0c4dcc4ea16d4fed3f34502)

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

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
openthread/ot-nrf528xx,openthread/ot-nrf528xx