Bump third_party/ot-br-posix/repo from `58822dc` to `02421b0` (#31587)

Bumps [third_party/ot-br-posix/repo](https://github.com/openthread/ot-br-posix) from `58822dc` to `02421b0`.
- [Release notes](https://github.com/openthread/ot-br-posix/releases)
- [Commits](https://github.com/openthread/ot-br-posix/compare/58822dce1934568523bf1389c039f249e1d979ad...02421b0ea6422a71150f786168a470d5d87a6d81)

---
updated-dependencies:
- dependency-name: third_party/ot-br-posix/repo
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
diff --git a/third_party/ot-br-posix/repo b/third_party/ot-br-posix/repo
index 58822dc..02421b0 160000
--- a/third_party/ot-br-posix/repo
+++ b/third_party/ot-br-posix/repo
@@ -1 +1 @@
-Subproject commit 58822dce1934568523bf1389c039f249e1d979ad
+Subproject commit 02421b0ea6422a71150f786168a470d5d87a6d81