chore: specify blank_line_between_import_groups to php-cs-fixer v2

Author: phil-davis

.php_cs.dist

@@ -12,6 +12,7 @@ $config->setRules([
             'class', 'function', 'const',
         ],
     ],
+    'blank_line_between_import_groups' => true,
 ]);
 
 return $config;