submodule: bump openthread from c2d5265 to d83ddf7

Bumps [openthread](https://github.com/openthread/openthread) from `c2d5265` to `d83ddf7`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@c2d5265...d83ddf7)

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

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