Update WebRTC code version (2021-06-18T04:03:27).

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

Bug: None
Change-Id: Icd2faaa16bee1217af5c8e22db125aff1efb5f7c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/223000
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/master@{#34328}

call/version.cc

diff --git a/call/version.cc b/call/version.cc
index d0e147d..9fdc499 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 2021-06-17T04:05:50";
+const char* const kSourceTimestamp = "WebRTC source stamp 2021-06-18T04:03:27";
 
 void LoadWebRTCVersionInRegister() {
   // Using volatile to instruct the compiler to not optimize `p` away even