submodule: bump openthread from `eca7a63` to `78e3b28` (#301)
submodule: bump openthread from `eca7a63` to `78e3b28` (#301)

Bumps [openthread](https://github.com/openthread/openthread) from `eca7a63` to `78e3b28`.
- [Commits](https://github.com/openthread/openthread/compare/eca7a63adcd035766995464daa2306863a76fc02...78e3b2812744ededc126c1d12f5d67fdf3ee7f30)

---
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-kw41z,openthread/ot-kw41z