Test object unset on test completion

The tearDown() function was kept empty without releasing resources of current object

Signed-off-by: A V Minhaz <minhazav@gmail.com>

test/classes/PMA_Config_test.php

@@ -57,6 +57,7 @@ class PMA_ConfigTest extends PHPUnit_Framework_TestCase
      */
     protected function tearDown()
     {
+        unset($this->object);
     }
 
     /**