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/psr/container/composer.json

@@ -8,20 +8,15 @@
     "authors": [
         {
             "name": "PHP-FIG",
-            "homepage": "http://www.php-fig.org/"
+            "homepage": "https://www.php-fig.org/"
         }
     ],
     "require": {
-        "php": ">=5.3.0"
+        "php": ">=7.2.0"
     },
     "autoload": {
         "psr-4": {
             "Psr\\Container\\": "src/"
         }
-    },
-    "extra": {
-        "branch-alias": {
-            "dev-master": "1.0.x-dev"
-        }
     }
 }