submodule: bump openthread from `3e833c1` to `a9d43fa` (#19)
submodule: bump openthread from `3e833c1` to `a9d43fa` (#19)

Bumps [openthread](https://github.com/openthread/openthread) from `3e833c1` to `a9d43fa`.
- [Commits](https://github.com/openthread/openthread/compare/3e833c120ff9dda92af315406266c453d2ac3699...a9d43fac5da39cc108cb3b57eb7df835db611c80)

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

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
openthread/ot-cc13x2-cc26x2,openthread/ot-cc13x2-cc26x2