fix(@libp2p/webrtc): use correct udp port in remote address (libp2p#2055

)

Use the UDP port in the remote address parsed from the last successful
ICE candidate.

packages/transport-webrtc/src/private-to-private/handler.ts

@@ -173,5 +173,5 @@ function parseRemoteAddress (sdp: string): string {
     return '/webrtc'
   }
 
-  return `/dnsaddr/${candidateParts[4]}/${candidateParts[2].toLowerCase()}/${candidateParts[3]}/webrtc`
+  return `/dnsaddr/${candidateParts[4]}/${candidateParts[2].toLowerCase()}/${candidateParts[5]}/webrtc`
 }