rector.php to update everything to PHP 7.4

[szepeviktor]

<?php

use Rector\Config\RectorConfig;
use Rector\Set\ValueObject\LevelSetList;

return static function (RectorConfig $rectorConfig): void {
    $rectorConfig->paths([
        __DIR__ . '/plugin-name.php',
        __DIR__ . '/src',
        __DIR__ . '/tests',
    ]);

    $rectorConfig->importNames();

    $rectorConfig->sets([
        LevelSetList::UP_TO_PHP_74,
    ]);
};