Use PHPUnit\Framework\TestCase instead of PHPUnit_Framework_TestCase (#202)

Author: carusogabriel

Tests/Psr6SessionHandlerTest.php

@@ -13,14 +13,15 @@
 
 use Cache\Adapter\PHPArray\ArrayCachePool;
 use Cache\SessionHandler\Psr6SessionHandler;
+use PHPUnit\Framework\TestCase;
 use Psr\Cache\CacheItemInterface;
 use Psr\Cache\CacheItemPoolInterface;
 
 /**
  * @author Aaron Scherer <[email protected]>
  * @author Tobias Nyholm <[email protected]>
  */
-class Psr6SessionHandlerTest extends \PHPUnit_Framework_TestCase
+class Psr6SessionHandlerTest extends TestCase
 {
     const TTL    = 100;
     const PREFIX = 'pre';