submodule: bump openthread from `b0e1712` to `d0bbfe6` (#6)
submodule: bump openthread from `b0e1712` to `d0bbfe6` (#6)

Bumps [openthread](https://github.com/openthread/openthread) from `b0e1712` to `d0bbfe6`.
- [Commits](https://github.com/openthread/openthread/compare/b0e1712d3b240981dc78f61356af8641dae5960f...d0bbfe6e4c0d173bd41423842dbb2f9bad6a2137)

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

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