Bump third_party/openthread/repo from `66eaeec` to `837c7fd` (#29900)

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `66eaeec` to `837c7fd`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](https://github.com/openthread/openthread/compare/66eaeec41a7090454a8825beff237844f5deca90...837c7fd357d3546f96b9b1433d8f1348371b242e)

---
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 66eaeec..837c7fd 160000
--- a/third_party/openthread/repo
+++ b/third_party/openthread/repo
@@ -1 +1 @@
-Subproject commit 66eaeec41a7090454a8825beff237844f5deca90
+Subproject commit 837c7fd357d3546f96b9b1433d8f1348371b242e