Add missing license header to fix checkstyle warning

Author: jjppp

src/test/java/pascal/taie/analysis/pta/PointerAnalysisResultTest.java

@@ -1,3 +1,25 @@
+/*
+ * Tai-e: A Static Analysis Framework for Java
+ *
+ * Copyright (C) 2022 Tian Tan <[email protected]>
+ * Copyright (C) 2022 Yue Li <[email protected]>
+ *
+ * This file is part of Tai-e.
+ *
+ * Tai-e is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation, either version 3
+ * of the License, or (at your option) any later version.
+ *
+ * Tai-e 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 Lesser General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Tai-e. If not, see <https://www.gnu.org/licenses/>.
+ */
+
 package pascal.taie.analysis.pta;
 
 import org.junit.jupiter.api.Test;