Add 'setUp(): void' declaration for PhpUnit 9 compatibility

Test/Integration/Model/Config/ConverterTest.php

@@ -13,7 +13,7 @@ class ConverterTest extends \PHPUnit\Framework\TestCase
      */
     protected $model;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->model = \Magento\TestFramework\Helper\Bootstrap::getObjectManager()
             ->create(Converter::class);

Test/Integration/Model/Config/Parser/Query/FetchMediaFilesChainTest.php

@@ -24,7 +24,7 @@ class FetchMediaFilesChainTest extends \PHPUnit\Framework\TestCase
      */
     private $parser2;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->parser1 = self::getMockBuilder(MediaFilesParserInterface::class)
             ->disableOriginalConstructor()

Test/Integration/Model/PageInstaller/TestCase.php

@@ -47,7 +47,7 @@ class TestCase extends \PHPUnit\Framework\TestCase
     protected $getFisrtPageByPageEntry;
 
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();