migration symfony 5 4 (#300)

* symfony 5.4 (diff dev)

* symfony 5.4 (working)

* symfony 5.4 (update autoload)

* symfony 5.4 (remove swiftmailer mailer implementation)

* symfony 5.4 (php doc and split Global accessor class)


### Impacted packages:

composer require php:">=7.2.5 <8.0.0" symfony/console:5.4.* symfony/dotenv:5.4.* symfony/framework-bundle:5.4.* symfony/twig-bundle:5.4.* symfony/yaml:5.4.* --update-with-dependencies

composer require symfony/stopwatch:5.4.* symfony/web-profiler-bundle:5.4.* --dev --update-with-dependencies

lib/symfony/css-selector/Parser/Shortcut/HashParser.php

@@ -31,7 +31,7 @@ class HashParser implements ParserInterface
     /**
      * {@inheritdoc}
      */
-    public function parse($source)
+    public function parse(string $source): array
     {
         // Matches an optional namespace, optional element, and required id
         // $source = 'test|input#ab6bd_field';