submodule: bump third_party/openthread/repo from `7e7da0e` to `742b4e8`
submodule: bump third_party/openthread/repo from `7e7da0e` to `742b4e8`

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `7e7da0e` to `742b4e8`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](https://github.com/openthread/openthread/compare/7e7da0e21149925d42f26f2e563e15c0b17226b2...742b4e8cc33b40ee6d6f4bfd8d2a101def5b2189)

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

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
openthread/borderrouter,openthread/ot-br-posix,openthread/ot-br-posix,openthread/borderrouter,openthread/borderrouter,openthread/borderrouter,openthread/borderrouter,openthread/ot-br-posix,openthread/ot-br-posix,openthread/ot-br-posix,openthread/borderrouter,openthread/ot-br-posix