Update WebRTC code version (2023-08-19T04:03:39).

Bug: None
Change-Id: I426c392cbbb1bee7266e25983fd039c6668a740b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/316904
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@{#40576}

call/version.cc

diff --git a/call/version.cc b/call/version.cc
index f341e1e..621e263 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 2023-08-18T04:05:33";
+const char* const kSourceTimestamp = "WebRTC source stamp 2023-08-19T04:03:39";
 
 void LoadWebRTCVersionInRegister() {
   // Using volatile to instruct the compiler to not optimize `p` away even