Bump third_party/openthread/repo from 0019f38 to 7d488bc

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `0019f38` to `7d488bc`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@0019f38...7d488bc)

---
updated-dependencies:
- dependency-name: third_party/openthread/repo
  dependency-type: direct:production
...

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

Author: dependabot[bot]

third_party/openthread/repo

@@ -0,0 +1 @@
+7d488bcf244eca8944b0f07e33a97690d5a2798e