N°3091 Update PHPUnit to 8.5 : fix setUp and teardDown methods signatures

"Return type declaration must be compatible with parent"
See https://phpunit.de/announcements/phpunit-8.html "Return Type of Template Methods"

test/core/CMDBSource/CMDBSourceTest.php

@@ -20,7 +20,7 @@ use utils;
  */
 class CMDBSourceTest extends ItopTestCase
 {
-	protected function setUp()
+	protected function setUp(): void
 	{
 
 		parent::setUp();