Deprecated mysql_ function

Here’s a deprecated function, it’s getting logged every time I access the support section:

<b>Warning</b>: mysql_get_server_info(): Access denied for user 'root'@'localhost' (using password: NO) in <b>/home/xxxxx/public_html/wp-content/plugins/tweet-old-post/inc/core.php</b> on line <b>1018</b><br />

I am using this in one of my plugins:

echo '<small>You are using PHP version ' . PHP_VERSION . ' and MySQL server version ' . mysqli_get_client_info() . '.</small>';

Looking forward for an updated version!

https://ww.wp.xz.cn/plugins/tweet-old-post/