chore: update Fixer config (#29)

Author: keradus

.php-cs-fixer.php renamed to .php-cs-fixer.dist.php

@@ -1,5 +1,18 @@
 <?php
 
+/*
+ * This file is part of PHP CS Fixer / PHPUnit Constraint XmlMatchesXsd.
+ *
+ * (c) SpacePossum
+ *     Dariusz Rumiński <[email protected]>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+use PhpCsFixer\Config;
+use PhpCsFixer\Finder;
+
 $header = <<<'EOF'
 This file is part of PHP CS Fixer / PHPUnit Constraint XmlMatchesXsd.
 
@@ -10,12 +23,13 @@
 with this source code in the file LICENSE.
 EOF;
 
-$finder = PhpCsFixer\Finder::create()
+$finder = Finder::create()
     ->exclude('tests/Fixtures')
     ->in(__DIR__)
+    ->append([__FILE__])
 ;
 
-return (new PhpCsFixer\Config())
+return (new Config())
     ->setRiskyAllowed(true)
     ->setRules([
         '@PhpCsFixer' => true,