submodule: bump openthread from `3a125c6` to `8907cb8` (#274)
submodule: bump openthread from `3a125c6` to `8907cb8` (#274)

Bumps [openthread](https://github.com/openthread/openthread) from `3a125c6` to `8907cb8`.
- [Commits](https://github.com/openthread/openthread/compare/3a125c66d28ab05d20f51d0279db3221976bcfc4...8907cb8495a827a82700a6e6af0ed5957c9b7f9c)

---
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-qorvo,openthread/ot-qorvo,openthread/ot-qorvo