Add Symfony 5 (#160)

Author: andreybolonin

Diff for: composer.json

@@ -3,14 +3,14 @@
     "license": "MIT",
     "require": {
         "php-pm/php-pm": "^2.0",
-        "symfony/http-foundation": "^3.4|^4.0",
-        "symfony/http-kernel": "^3.4|^4.0",
+        "symfony/http-foundation": "^3.4|^4.0|^5.0",
+        "symfony/http-kernel": "^3.4|^4.0|^5.0",
         "guzzlehttp/psr7": "^1.5"
     },
     "require-dev": {
         "phpunit/phpunit": "^7.0",
-        "symfony/framework-bundle": "^3.4|^4.0",
-        "symfony/yaml": "^3.4|^4.0",
+        "symfony/framework-bundle": "^3.4|^4.0|^5.0",
+        "symfony/yaml": "^3.4|^4.0|^5.0",
         "doctrine/annotations": "^1.6"
     },
     "autoload": {