fix: proxy-groups filter logic

adapter/outboundgroup/relay.go

@@ -19,6 +19,10 @@ type Relay struct {
 	filter    string
 }
 
+func (r *Relay) IsProxyGroup() bool {
+	return true
+}
+
 // DialContext implements C.ProxyAdapter
 func (r *Relay) DialContext(ctx context.Context, metadata *C.Metadata, opts ...dialer.Option) (C.Conn, error) {
 	var proxies []C.Proxy