submodule: bump openthread from `8a0e7b8` to `7b07dc5` (#27)
submodule: bump openthread from `8a0e7b8` to `7b07dc5` (#27)

Bumps [openthread](https://github.com/openthread/openthread) from `8a0e7b8` to `7b07dc5`.
- [Commits](https://github.com/openthread/openthread/compare/8a0e7b8c4e02f0b5cc058b69b14c2261db9c1cea...7b07dc503bf7228238451b919d2a0728bcda77e9)

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

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
openthread/ot-samr21,openthread/ot-samr21