Allow to use Symfony 5 (#26)

Author: evertharmeling

composer.json

@@ -19,8 +19,8 @@
  "sendgrid/sendgrid": "^7.0",
  "sendgrid/php-http-client": "~3.9.4",
  "symfony/swiftmailer-bundle": "~3.2",
- "symfony/framework-bundle": "~2.7|~3.3|~4.0",
- "symfony/yaml": "~2.7|~3.3|~4.0"
+ "symfony/framework-bundle": "~2.7|~3.3|~4.0|~5.0",
+ "symfony/yaml": "~2.7|~3.3|~4.0|~5.0"
  },
  "require-dev": {
  "nyholm/symfony-bundle-test": "^1.3"