Update WebRTC code version (2024-01-21T04:12:31).

Bug: None
Change-Id: I77f9322f145cf874aec8687f7939f5c37cbb74d0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/335348
Bot-Commit: webrtc-version-updater@webrtc-ci.iam.gserviceaccount.com <webrtc-version-updater@webrtc-ci.iam.gserviceaccount.com>
Commit-Queue: webrtc-version-updater@webrtc-ci.iam.gserviceaccount.com <webrtc-version-updater@webrtc-ci.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#41588}

call/version.cc

diff --git a/call/version.cc b/call/version.cc
index 3db08eb..85fdf00 100644
--- a/call/version.cc
+++ b/call/version.cc
@@ -13,7 +13,7 @@
 namespace webrtc {
 
 // The timestamp is always in UTC.
-const char* const kSourceTimestamp = "WebRTC source stamp 2024-01-20T04:12:27";
+const char* const kSourceTimestamp = "WebRTC source stamp 2024-01-21T04:12:31";
 
 void LoadWebRTCVersionInRegister() {
   // Using volatile to instruct the compiler to not optimize `p` away even