submodule: bump openthread from c0690e7 to bd310db

Bumps [openthread](https://github.com/openthread/openthread) from `c0690e7` to `bd310db`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@c0690e7...bd310db)

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

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