Revert "Update NEWS/UPGRADING for __sleep() deprecation"

This reverts commit 4191843.

Author: nicolas-grekas

UPGRADING

@@ -401,10 +401,6 @@ PHP 8.5 UPGRADE NOTES
     $_GET or $_SERVER['QUERY_STRING'] to access the information, after verifying
     that the usage is safe.
     RFC: https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_the_register_argc_argv_ini_directive
-  . The __sleep() magic method has been deprecated. The __serialize() magic
-    method should be used instead, or at the same time if compatibility with
-    PHP 7 is required.
-    RFC: https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_the_sleep_and_wakeup_magic_methods
 
 - Curl:
   . The curl_close() function has been deprecated, as CurlHandle objects are