submodule: bump openthread from b4282a8 to 0485be3

Bumps [openthread](https://github.com/openthread/openthread) from `b4282a8` to `0485be3`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@b4282a8...0485be3)

---
updated-dependencies:
- dependency-name: openthread
  dependency-version: '0485be36a4696b8df11bca8022c2643cbe390b21'
  dependency-type: direct:production
...

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Author: dependabot[bot]