submodule: bump openthread from `ab28382` to `7a1c843` (#195)
submodule: bump openthread from `ab28382` to `7a1c843` (#195)

Bumps [openthread](https://github.com/openthread/openthread) from `ab28382` to `7a1c843`.
- [Commits](https://github.com/openthread/openthread/compare/ab2838211383d2c52f00399ce07ce31cf72f1d64...7a1c843ffd07e59b1b0ffe907cee1f9418eebdec)

---
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-samr21,openthread/ot-samr21