Merge branch '7.3' into 7.4

* 7.3:
  fix package name in deprecation message
  [Intl] Fix locale validator when canonicalize is true
  Update GitHub PR template
  [FrameworkBundle] also deprecate the internal rate limiter factory alias
  [Notifier] Update fake SMS transports to use contracts event dispatcher.
  [VarDumper] Remove duplicate default caster for Socket

Author: nicolas-grekas

Cloner/AbstractCloner.php

@@ -203,8 +203,6 @@ abstract class AbstractCloner implements ClonerInterface
 
         'XmlParser' => ['Symfony\Component\VarDumper\Caster\XmlResourceCaster', 'castXml'],
 
-        'Socket' => ['Symfony\Component\VarDumper\Caster\SocketCaster', 'castSocket'],
-
         'RdKafka' => ['Symfony\Component\VarDumper\Caster\RdKafkaCaster', 'castRdKafka'],
         'RdKafka\Conf' => ['Symfony\Component\VarDumper\Caster\RdKafkaCaster', 'castConf'],
         'RdKafka\KafkaConsumer' => ['Symfony\Component\VarDumper\Caster\RdKafkaCaster', 'castKafkaConsumer'],