FIX Symfony kernel tests

The kernel.secret parameter is not defined anymore.
The tests use a testing container to avoid deprecation notices.
PHP and Symfony versions now contain up to PHP 8.0 and Symfony 5.3

Author: AymDev

.github/workflows/ci.yml

@@ -7,7 +7,7 @@ jobs:
         runs-on: ubuntu-latest
         strategy:
             matrix:
-                php: ['7.3', '7.4']
+                php: ['7.3', '7.4', '8.0']
 
         steps:
             # Setup

.github/workflows/installation.yml

@@ -7,8 +7,11 @@ jobs:
         runs-on: ubuntu-latest
         strategy:
             matrix:
-                php: ['7.2', '7.3', '7.4']
-                symfony: ['4.4', '5.0', '5.1']
+                php: ['7.2', '7.3', '7.4', '8.0']
+                symfony: ['4.4', '5.0', '5.1', '5.2', '5.3']
+                exclude:
+                    - php: '8.0'
+                      symfony: '5.0'
 
         steps:
             # Setup

tests/DependencyInjection/Compiler/ConvertersPassTest.php

@@ -10,6 +10,7 @@
 use League\CommonMark\Extension\InlinesOnly\InlinesOnlyExtension;
 use PHPUnit\Framework\TestCase;
 use Symfony\Bundle\FrameworkBundle\FrameworkBundle;
+use Symfony\Bundle\TwigBundle\DependencyInjection\TwigExtension;
 use Symfony\Bundle\TwigBundle\TwigBundle;
 use Symfony\Component\Config\Loader\LoaderInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
@@ -89,7 +90,7 @@ public function testTwigExtensionRegistration()
             ]
         ]);
         $kernel->boot();
-        $container = $kernel->getContainer();
+        $container = $kernel->getContainer()->get('test.service_container');
 
         /** @var Environment $twig */
         $twig = $container->get('twig');
@@ -163,6 +164,12 @@ public function registerContainerConfiguration(LoaderInterface $loader)
     {
         $loader->load(function (ContainerBuilder $container) {
             $container->loadFromExtension('aymdev_commonmark', $this->aymdevCommonmarkConfig);
+
+            // Parameter is undefined but required
+            $container->setParameter('kernel.secret', '$ecret');
+
+            // Makes the test.service_container service available
+            $container->prependExtensionConfig('framework', ['test' => true]);
         });
     }