protected static function generateConfig($releases, $phpFile)
    {
        $data = '<?php' . PHP_EOL;
        $data .= '// DO NOT EDIT! This file has been automatically generated.' . PHP_EOL;
        $data .= '// Run composer update to fetch a new version.' . PHP_EOL;
        $data .= 'return array(' . PHP_EOL;
        foreach ($releases as $version => $date) {
            $data .= '   \'' . $version . '\' => \'' . $date . '\',' . PHP_EOL;
        }
        $data .= ');' . PHP_EOL;

        file_put_contents($phpFile, $data);
    }