network, yuzu: Make copyright headers SPDX-compliant

src/yuzu/multiplayer/moderation_dialog.cpp

@@ -1,6 +1,5 @@
-// Copyright 2018 Citra Emulator Project
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
+// SPDX-FileCopyrightText: Copyright 2018 Citra Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <QStandardItem>
 #include <QStandardItemModel>