submodule: bump openthread from 7673194 to 07a1b7b (#797)

Bumps [openthread](https://github.com/openthread/openthread) from `7673194` to `07a1b7b`.
- [Commits](openthread/openthread@7673194...07a1b7b)

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

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