Support PHPUnit 6

tests/Spout/Reader/XLSX/ReaderTest.php

@@ -6,11 +6,12 @@ use Box\Spout\Common\Exception\IOException;
 use Box\Spout\Common\Type;
 use Box\Spout\Reader\Common\Creator\EntityFactory;
 use Box\Spout\TestUsingResource;
+use PHPUnit\Framework\TestCase;
 
 /**
  * Class ReaderTest
  */
-class ReaderTest extends \PHPUnit_Framework_TestCase
+class ReaderTest extends TestCase
 {
     use TestUsingResource;