[Maintenance] Fix ecs and phpstan (#424)

Author: TheMilek

ecs.php

@@ -23,11 +23,10 @@
     $config->import('vendor/sylius-labs/coding-standard/ecs.php');
 
     $config->parallel();
-    $config->paths(['src', 'spec']);
+    $config->paths(['src', 'tests/DependencyInjection', 'tests/Unit', 'tests/Behat']);
     $config->skip([
         InlineDocCommentDeclarationSniff::class . '.MissingVariable',
         InlineDocCommentDeclarationSniff::class . '.NoAssignment',
-        VisibilityRequiredFixer::class => ['*Spec.php'],
         '**/var/*',
         'src/Migrations/*',
     ]);

phpstan.neon

@@ -17,4 +17,5 @@ parameters:
         - '/Method Sylius\\InvoicingPlugin\\[a-zA-Z\\]+::getFlashBag\(\) should return Symfony\\Component\\HttpFoundation\\Session\\Flash\\FlashBagInterface but returns Symfony\\Component\\HttpFoundation\\Session\\SessionBagInterface\./'
         - '/Method Sylius\\InvoicingPlugin\\Security\\Voter\\InvoiceVoter::supports\(\) has parameter \$attribute with no typehint specified./'
         - '/Method Sylius\\InvoicingPlugin\\Security\\Voter\\InvoiceVoter::supports\(\) has parameter \$subject with no typehint specified./'
+        - '/Call to method scalarNode\(\) on an unknown class Symfony\\Component\\Config\\Definition\\Builder\\NodeBuilder<Symfony\\Component\\Config\\Definition\\Builder\\ArrayNodeDefinition>./'
         - '/expects string, string\|null given\.$/'