Fix Kernel in PHPUnit config

Author: GSadee

phpunit.xml.dist

@@ -18,6 +18,6 @@
         <env name="APP_ENV" value="test"/>
         <env name="SHELL_VERBOSITY" value="-1" />
 
-        <server name="KERNEL_CLASS" value="Tests\Sylius\InvoicingPlugin\Application\Kernel" />
+        <server name="KERNEL_CLASS" value="Sylius\TestApplication\Kernel" />
     </php>
 </phpunit>