Rule source on GitHub

DowngradeTrailingCommasInFunctionCallsRector

Remove trailing commas in function calls

 class SomeClass
 {
     public function __construct(string $value)
     {
         $compacted = compact(
             'posts',
-            'units',
+            'units'
         );
     }
 }

Configure your rector.php:

<?php

use Rector\Config\RectorConfig;
use Rector\DowngradePhp73\Rector\FuncCall\DowngradeTrailingCommasInFunctionCallsRector;

return RectorConfig::configure()
    ->withRules([
        DowngradeTrailingCommasInFunctionCallsRector::class,
    ]);