Update WebRTC code version (2021-09-13T04:03:47).

TBR=webrtc-version-updater@webrtc-ci.iam.gserviceaccount.com,mbonadei@webrtc.org

Bug: None
Change-Id: Iab72a24b1b187a1a9a57b3b3c14905df2f75729d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/231822
Reviewed-by: 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@{#34975}
diff --git a/call/version.cc b/call/version.cc
index d9e9ff7..72501b3 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 2021-09-12T04:02:50";
+const char* const kSourceTimestamp = "WebRTC source stamp 2021-09-13T04:03:47";
 
 void LoadWebRTCVersionInRegister() {
   // Using volatile to instruct the compiler to not optimize `p` away even