PHP 8.x compat issue

Howdy! While prepping for a migration from PHP 7.4 to PHP 8.3, I ran across an error with a couple lines of code in this plugin. I have a feeling that neither are really being triggered, but I though it was worth reaching out to let you know.

First, in functions.php, the sanitize_array() function uses $this->sanitize_array() in an attempt to call itself when a nested array is encountered. This $this-> usage inside a function has not worked since PHP 7.1 and causes a fatal error. My guess is that the plugin never actually processes a nested array through here, but it seems like a good defensive move to make the syntax right.

Similarly, in qc-support-promo-page/qc-clr-recommendbot-support-plugin.php, $this-> is used the same way in an AJAX action that retrieves a list of promoted plugins. I have not actually tested that AJAX call, but it seems like a pretty quick fix as well.

Thank you!