use PHPUnit\Framework\TestCase;

 final class SomeClass extends TestCase
 {
     public function testMethod(): void
     {
-        $this->assertContainsOnly('string', ['a', 'b']);
+        $this->assertContainsOnlyString(['a', 'b']);
     }
 }

Configure your rector.php:

<?php

use Rector\Config\RectorConfig;
use Rector\PHPUnit\PHPUnit110\Rector\CallLike\AssertContainsOnlyMethodCallRector;

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

SETS:  phpunit/phpunit 11.0 phpunit/phpunit 12.0 phpunit/phpunit 13.0 phpunit/phpunit >=4.0