Fix to stay in symfony 4.3

Some libs are not yet available with out errors for symfony 4.4
php-http/httplug-bundle, sonata-project/core-bundle, etc.

composer.json

@@ -61,12 +61,14 @@
         "ezyang/htmlpurifier": "~4.10",
         "sensio/framework-extra-bundle": "~5.0",
         "sensiolabs/security-checker": "~6.0",
+
         "symfony/asset": "^4.0",
         "symfony/dotenv": "^4.0",
         "symfony/expression-language": "^4.0",
         "symfony/flex": "^1.0",
         "symfony/form": "^4.0",
         "symfony/framework-bundle": "^4.0",
+        "symfony/http-kernel": "4.3.*",
         "symfony/monolog-bundle": "^3.1",
         "symfony/polyfill-apcu": "^1.9",
         "symfony/security-bundle": "^4.0",
@@ -77,6 +79,7 @@
         "symfony/validator": "^4.0",
         "symfony/webpack-encore-bundle": "^1.1",
         "symfony/yaml": "^4.0",
+
         "tgalopin/html-sanitizer-bundle": "^1.1",
         "twig/extensions": "^1.5",