Update WebRTC code version (2021-09-03T04:04:41).

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

Bug: None
Change-Id: I4174c95d0e7aba28bac3873d1a4f2ee3769b54b0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/231106
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@{#34912}

call/version.cc

diff --git a/call/version.cc b/call/version.cc
index 374e412..7b438ae 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 2021-08-31T04:06:38";
+const char* const kSourceTimestamp = "WebRTC source stamp 2021-09-03T04:04:40";
 
 void LoadWebRTCVersionInRegister() {
   // Using volatile to instruct the compiler to not optimize `p` away even