Merge pull request #127 from CurrencyCloud/SDKPHP-101-symfony-yaml-v5-update

SDKPHP-101 symfony yaml v5 update

Author: gergelykovacs

composer.json

@@ -16,7 +16,7 @@
   "require": {
     "php": ">=7.2",
     "guzzlehttp/guzzle": "~6.1||~7.0",
-    "symfony/yaml": "^2.7||^3.0||^4.0",
+    "symfony/yaml": "^2.7||^3.0||^4.0||^5.0",
     "symfony/event-dispatcher": "^5.0"
   },
   "require-dev": {