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

Matcher/Dumper/StaticPrefixCollection.php

@@ -147,7 +147,7 @@ private function getCommonPrefix(string $prefix, string $anotherPrefix): array
         $baseLength = \strlen($this->prefix);
         $end = min(\strlen($prefix), \strlen($anotherPrefix));
         $staticLength = null;
-        set_error_handler([__CLASS__, 'handleError']);
+        set_error_handler(self::handleError(...));
 
         try {
             for ($i = $baseLength; $i < $end && $prefix[$i] === $anotherPrefix[$i]; ++$i) {