Laravel 9 Support

Author: hailwood

composer.json

@@ -21,7 +21,7 @@
     "require": {
         "php": "^7.3|^8.0",
         "xeroapi/xero-php-oauth2": "^2.0",
-        "laravel/framework": "^5.5|^6.0|^7.0|^8.0"
+        "laravel/framework": "^5.5|^6.0|^7.0|^8.0|^9.0"
     },
     "require-dev": {
         "symfony/var-dumper": "^4.3",