Symfony 5 support added (php-debugbar#431)

Author: jzawadzki

composer.json

@@ -19,7 +19,7 @@
     "require": {
         "php": "^7.1",
         "psr/log": "^1.0",
-        "symfony/var-dumper": "^2.6|^3|^4"
+        "symfony/var-dumper": "^2.6|^3|^4|^5"
     },
     "require-dev": {
         "phpunit/phpunit": "^5"