[test] Fix memory leak

Author: hazendaz

src/test/java/org/apache/ibatis/io/ExternalResourcesTest.java

@@ -86,6 +86,7 @@ public void testGetConfiguredTemplate() {
       FileWriter fileWriter = new FileWriter(tempFile);
       fileWriter.append("new_command.template=templates/col_new_template_migration.sql");
       fileWriter.flush();
+      fileWriter.close();
       templateName = ExternalResources.getConfiguredTemplate(tempFile.getAbsolutePath(), "new_command.template");
       assertEquals("templates/col_new_template_migration.sql", templateName);
     } catch (Exception e) {