submodule: bump third_party/openthread/repo from `e04c8e3` to `215c459` (#1215)

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `e04c8e3` to `215c459`.
- [Commits](https://github.com/openthread/openthread/compare/e04c8e330773cf3fcc1acd00b18e7ea355e134ad...215c459846bcd9d7f167bb55ba252cc8372dc107)

---
updated-dependencies:
- dependency-name: third_party/openthread/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/openthread/repo b/third_party/openthread/repo
index e04c8e3..215c459 160000
--- a/third_party/openthread/repo
+++ b/third_party/openthread/repo
@@ -1 +1 @@
-Subproject commit e04c8e330773cf3fcc1acd00b18e7ea355e134ad
+Subproject commit 215c459846bcd9d7f167bb55ba252cc8372dc107