chore: rename deprecated php-cs-fixer rulesets

Author: deviantintegral

.php-cs-fixer.dist.php

@@ -2,8 +2,8 @@
 
 return (new PhpCsFixer\Config())
     ->setRules([
-        '@PHP71Migration' => true,
-        '@PHPUnit75Migration:risky' => true,
+        '@PHP7x1Migration' => true,
+        '@PHPUnit7x5Migration:risky' => true,
         '@Symfony' => true,
         '@Symfony:risky' => true,
         'protected_to_private' => false,