submodule: bump openthread from 3905006 to 85aff45

Bumps [openthread](https://github.com/openthread/openthread) from `3905006` to `85aff45`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@3905006...85aff45)

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

Signed-off-by: dependabot[bot] <[email protected]>