ci: add php cs fixer

.php-cs-fixer.dist.php

@@ -0,0 +1,13 @@
+<?php
+
+$finder = (new PhpCsFixer\Finder())
+    ->in(__DIR__)
+    ->exclude('var')
+;
+
+return (new PhpCsFixer\Config())
+    ->setRules([
+        '@Symfony' => true,
+    ])
+    ->setFinder($finder)
+;