Merge branch '6.3' into 6.4

* 6.3:
  [AssetMapper] Fixing import parsing from jsdelivr
  Fix htaccess sample to use index.php instead of app.php
  [SecurityBundle] Add `firewalls.logout.csrf_token_manager` to XSD
  [Form] Fix form events phpdocs
  fix(mailgun-smtp): disable tls for mailgun as it should use starttls instead

Transport/MailgunSmtpTransport.php

@@ -24,7 +24,7 @@ class MailgunSmtpTransport extends EsmtpTransport
 
     public function __construct(string $username, #[\SensitiveParameter] string $password, string $region = null, EventDispatcherInterface $dispatcher = null, LoggerInterface $logger = null)
     {
-        parent::__construct('us' !== ($region ?: 'us') ? sprintf('smtp.%s.mailgun.org', $region) : 'smtp.mailgun.org', 587, true, $dispatcher, $logger);
+        parent::__construct('us' !== ($region ?: 'us') ? sprintf('smtp.%s.mailgun.org', $region) : 'smtp.mailgun.org', 587, false, $dispatcher, $logger);
 
         $this->setUsername($username);
         $this->setPassword($password);