core: Fix ListenQUIC listener key conflict

Reported on commit e3e8aab

Abused this change in some bash for loops to rapidly reload config
while making requests and didn't observe any memory or resource leaks.

listeners.go

@@ -436,7 +436,7 @@ func ListenPacket(network, addr string) (net.PacketConn, error) {
 //
 // TODO: See if we can find a more elegant solution closer to the new NetworkAddress.Listen API.
 func ListenQUIC(ln net.PacketConn, tlsConf *tls.Config, activeRequests *int64) (quic.EarlyListener, error) {
-	lnKey := listenerKey(ln.LocalAddr().Network(), ln.LocalAddr().String())
+	lnKey := listenerKey("quic+"+ln.LocalAddr().Network(), ln.LocalAddr().String())
 
 	sharedEarlyListener, _, err := listenerPool.LoadOrNew(lnKey, func() (Destructor, error) {
 		earlyLn, err := quic.ListenEarly(ln, http3.ConfigureTLSConfig(tlsConf), &quic.Config{
@@ -451,7 +451,6 @@ func ListenQUIC(ln net.PacketConn, tlsConf *tls.Config, activeRequests *int64) (
 		if err != nil {
 			return nil, err
 		}
-
 		return &sharedQuicListener{EarlyListener: earlyLn, key: lnKey}, nil
 	})
 	if err != nil {