Fix return type of DateTimeImmutable::__set_state()

Author: kocsismate

ext/date/php_date.stub.php

@@ -251,7 +251,7 @@ public function __construct(string $datetime = "now", ?DateTimeZone $timezone =
     /** @return void */
     public function __wakeup() {}
 
-    /** @return DateTimeZone */
+    /** @return DateTimeImmutable */
     public static function __set_state(array $array) {}
 
     /**

ext/date/php_date_arginfo.h

@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 7b23a03d3c4941fb9a614de62d80fa5b0e11d14b */
+ * Stub hash: 339c2c91f38eeaafac6134ac04573243069502f5 */
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_MASK_EX(arginfo_strtotime, 0, 1, MAY_BE_LONG|MAY_BE_FALSE)
 	ZEND_ARG_TYPE_INFO(0, datetime, IS_STRING, 0)