Docs: Correct the expected parameter type for `WP_Customize_Manager::remove_preview_signature()`.

Before the method was deprecated, the parameter contained the value passed through for the `wp_die_handler` filter, which expects a callable function. 

Follow-up to [20926], [32535], [34320], [38810], [53242], [53243].

See #54729.
Built from https://develop.svn.wordpress.org/trunk@53244


git-svn-id: http://core.svn.wordpress.org/trunk@52833 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-customize-manager.php

@@ -2235,8 +2235,9 @@ final class WP_Customize_Manager {
 	 * @since 3.4.0
 	 * @deprecated 4.7.0
 	 *
-	 * @param mixed $callback Value passed through for {@see 'wp_die_handler'} filter.
-	 * @return mixed Value passed through for {@see 'wp_die_handler'} filter.
+	 * @param callable|null $callback Optional. Value passed through for {@see 'wp_die_handler'} filter.
+	 *                                Default null.
+	 * @return callable|null Value passed through for {@see 'wp_die_handler'} filter.
 	 */
 	public function remove_preview_signature( $callback = null ) {
 		_deprecated_function( __METHOD__, '4.7.0' );

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.0-beta2-53243';
+$wp_version = '6.0-beta2-53244';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.