Bump third_party/libdatachannel/repo from `65e1315` to `3e9bf68` (#38438)

Bumps [third_party/libdatachannel/repo](https://github.com/paullouisageneau/libdatachannel) from `65e1315` to `3e9bf68`.
- [Release notes](https://github.com/paullouisageneau/libdatachannel/releases)
- [Commits](https://github.com/paullouisageneau/libdatachannel/compare/65e1315bb0473d7253357aad6934473e0d4a6f9f...3e9bf686920cbff994b7103e7864f59ef93f4dff)

---
updated-dependencies:
- dependency-name: third_party/libdatachannel/repo
  dependency-version: 3e9bf686920cbff994b7103e7864f59ef93f4dff
  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/libdatachannel/repo b/third_party/libdatachannel/repo
index 65e1315..3e9bf68 160000
--- a/third_party/libdatachannel/repo
+++ b/third_party/libdatachannel/repo
@@ -1 +1 @@
-Subproject commit 65e1315bb0473d7253357aad6934473e0d4a6f9f
+Subproject commit 3e9bf686920cbff994b7103e7864f59ef93f4dff