submodule: bump openthread from 0e0a497 to 7f4c7fc (#612)

Bumps [openthread](https://github.com/openthread/openthread) from `0e0a497` to `7f4c7fc`.
- [Commits](openthread/openthread@0e0a497...7f4c7fc)

---
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>