[update] Code style update

Author: Angelaon

.php_cs.dist

@@ -3,9 +3,12 @@
 return PhpCsFixer\Config::create()
     ->setRules([
         '@PSR2' => true,
+        '@PSR12' => true,
         'array_syntax' => ['syntax' => 'short']
     ])
     ->setFinder(
-        PhpCsFixer\Finder::create()->in(__DIR__ . '/src')
+        PhpCsFixer\Finder::create()
+            ->in(__DIR__ . '/src')
+            ->in(__DIR__ . '/tests')
     )
 ;