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/routing/Generator/ConfigurableRequirementsInterface.php

@@ -20,7 +20,7 @@ namespace Symfony\Component\Routing\Generator;
  * The possible configurations and use-cases:
  * - setStrictRequirements(true): Throw an exception for mismatching requirements. This
  *   is mostly useful in development environment.
- * - setStrictRequirements(false): Don't throw an exception but return null as URL for
+ * - setStrictRequirements(false): Don't throw an exception but return an empty string as URL for
  *   mismatching requirements and log the problem. Useful when you cannot control all
  *   params because they come from third party libs but don't want to have a 404 in
  *   production environment. It should log the mismatch so one can review it.
@@ -40,10 +40,8 @@ interface ConfigurableRequirementsInterface
     /**
      * Enables or disables the exception on incorrect parameters.
      * Passing null will deactivate the requirements check completely.
-     *
-     * @param bool|null $enabled
      */
-    public function setStrictRequirements($enabled);
+    public function setStrictRequirements(?bool $enabled);
 
     /**
      * Returns whether to throw an exception on incorrect parameters.