add missing license

pallets/unified-accounts/src/migration.rs

@@ -1,3 +1,21 @@
+// This file is part of Astar.
+
+// Copyright (C) Stake Technologies Pte.Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+// Astar is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Astar is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Astar. If not, see <http://www.gnu.org/licenses/>.
+
 use super::{Config, Pallet, Weight};
 use astar_primitives::evm::EvmAddress;
 use frame_support::{