Bump WP requirement to 6.5

Author: ocean90

public-post-preview.php

@@ -7,7 +7,7 @@
  * Author URI: https://dominikschilling.de/
  * Plugin URI: https://github.com/ocean90/public-post-preview
  * Text Domain: public-post-preview
- * Requires at least: 6.4
+ * Requires at least: 6.5
  * Tested up to: 6.7
  * Requires PHP: 8.0
  * License: GPLv2 or later