Added Symfony5 support (#119)

Author: vahurk

composer.json

@@ -19,11 +19,11 @@
     "mtdowling/cron-expression": "^1.0",
     "swiftmailer/swiftmailer": "^5.4|^6.0",
     "jeremeamia/superclosure": "^2.2",
-    "symfony/process": "^2.7|^3.0|^4.0"
+    "symfony/process": "^2.7|^3.0|^4.0|^5.0"
   },
   "require-dev": {
     "phpunit/phpunit": "^4.6",
-    "symfony/filesystem": "^2.7|^3.0|^4.0"
+    "symfony/filesystem": "^2.7|^3.0|^4.0|^5.0"
   },
   "autoload": {
     "psr-4": {