submodule: bump openthread from 62cac82 to 64e0811

Bumps [openthread](https://github.com/openthread/openthread) from `62cac82` to `64e0811`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@62cac82...64e0811)

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

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