Update URI of TransportSequenceNumberV2

The previous URI was a placeholder and is not valid. The URI
https://webrtc.org/experiments/rtp-hdrext/transport-wide-cc-02/
must be used instead.

Bug: webrtc:10264
Change-Id: Ibabde599b5bbd116c1c5e86ba0c9c64019bf7026
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/126360
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Commit-Queue: Johannes Kron <kron@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27051}
diff --git a/api/rtp_parameters.cc b/api/rtp_parameters.cc
index 6177dd3..9ba2423 100644
--- a/api/rtp_parameters.cc
+++ b/api/rtp_parameters.cc
@@ -105,7 +105,7 @@
 const char RtpExtension::kTransportSequenceNumberUri[] =
     "http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01";
 const char RtpExtension::kTransportSequenceNumberV2Uri[] =
-    "http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-02";
+    "http://www.webrtc.org/experiments/rtp-hdrext/transport-wide-cc-02";
 
 // This extension allows applications to adaptively limit the playout delay
 // on frames as per the current needs. For example, a gaming application