fix: prevent goroutine leak by adding exit signal for RTCP PLI ticker (#697)

Co-authored-by: alvarorichard <alvarorichard@tuta.io>

server/internal/webrtc/manager.go

@@ -443,18 +443,27 @@ func (manager *WebRTCManagerCtx) CreatePeer(session types.Session) (*webrtc.Sess
 		ticker := time.NewTicker(rtcpPLIInterval)
 		defer ticker.Stop()
 
+		//ticker.Stop() does not close channel,so the channel,so the goroutine below needs
+		//its own singal to exit, otherwise it would block on the ticker channel forever and leak memory
+		done := make(chan struct{})
+		defer close(done)
+
 		go func() {
-			for range ticker.C {
+			for {
+				select {
+				case <-done:
+					return
+				case <-ticker.C:
 					err := connection.WriteRTCP([]rtcp.Packet{
 						&rtcp.PictureLossIndication{
 							MediaSSRC: uint32(track.SSRC()),
 						},
 					})
-
 					if err != nil {
 						logger.Err(err).Msg("remote track rtcp send err")
 					}
 				}
+			}
 		}()
 
 		buf := make([]byte, 1400)