Add PHPStan configuration for Symfony4 tests

- Created a new phpstan.neon file in the Symfony4 tests directory.
- Configured paths and excluded Symfony3 directory.
- Added bootstrap files for autoloading.
- Set dynamic constant names and adjusted reporting settings.
- Established PHPStan level to 6 for stricter analysis.

modules/empikmarketplace/upgrade/upgrade-2.1.1.php

@@ -0,0 +1,12 @@
+<?php
+
+use Empik\Marketplace\Adapter\ConfigurationAdapter;
+
+function upgrade_module_2_1_1($object)
+{
+    $return = true;
+
+    $return &= Configuration::updateValue(ConfigurationAdapter::CONF_DEFAULT_VAT_RATE, 23);
+
+    return $return;
+}