Merge branch '6.4' into 7.0

* 6.4:
  [Mime] Fix lowest versions of deps
  [VarDumper] Fix calling scope detection inside magic accessors
  [Validator] add missing German translations
  fix deprecation versions
  update the Brevo SMTP host
  Remove \ReflectionProperty::setAccessible(true) calls
  [Serializer] Fix denormalizing abstract part headers in MimeMessageNormalizer
  Fix property must not be accessed before initialization on SymfonyRuntime::$input
  [Form] Remove an obsolete phpdoc comment
  [Webhook] Allow slash in webhook type
  Use more "First class callable syntax" + Normalize set_error_handler/set_exception_handler calls
  [FrameworkBundle][Workflow] Throw exception is workflow.xxx.transitions is not an array

Author: nicolas-grekas

ErrorHandler.php

@@ -112,7 +112,7 @@ public static function register(self $handler = null, bool $replace = true): sel
     {
         if (null === self::$reservedMemory) {
             self::$reservedMemory = str_repeat('x', 32768);
-            register_shutdown_function(__CLASS__.'::handleFatalError');
+            register_shutdown_function(self::handleFatalError(...));
         }
 
         if ($handlerIsNew = null === $handler) {