FILTER_SANITIZE_STRING deprecated

The plugin uses FILTER_SANITIZE_STRING which was deprecated in PHP 8.1 and removed in PHP 8.2+.

File: modules/deepl-translate-post.php
Line: 79

Current code:

$nonce = filter_input( INPUT_GET, '_wpdeeplnonce', FILTER_SANITIZE_STRING );

Suggested fix:

$nonce = filter_input( INPUT_GET, '_wpdeeplnonce', FILTER_SANITIZE_FULL_SPECIAL_CHARS );

Or alternatively:

$nonce = isset( $_GET['_wpdeeplnonce'] ) ? htmlspecialchars( $_GET['_wpdeeplnonce'], ENT_QUOTES, 'UTF-8' ) : '';

Impact: Sites running PHP 8.1+ will see deprecation warnings. Sites running PHP 8.2+ will experience errors.

Environment:

• WordPress: 6.9
• PHP: 8.3
• Plugin version: 2.5.2

Thank you!

Didier.