submodule: bump openthread from b9dcdbc to 41526d5

Bumps [openthread](https://github.com/openthread/openthread) from `b9dcdbc` to `41526d5`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@b9dcdbc...41526d5)

---
updated-dependencies:
- dependency-name: openthread
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>