submodule: bump openthread from 7d488bc to 4c0af02

Bumps [openthread](https://github.com/openthread/openthread) from `7d488bc` to `4c0af02`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@7d488bc...4c0af02)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

openthread

@@ -0,0 +1 @@
+4c0af025132fa7553cb7ad97fde2808b4e7e469f