Tentative extra PHP 8.1 fix

Author: jrfnl

src/wp-includes/Requests/Cookie.php

@@ -261,6 +261,10 @@ protected function normalize_attribute($name, $value) {
 		switch (strtolower($name)) {
 			case 'expires':
 				// Expiration parsing, as per RFC 6265 section 5.2.1
+				if (is_null($value)) {
+					return null;
+				}
+
 				if (is_int($value)) {
 					return $value;
 				}