allow laravel7 install (#15)

Author: swilla

composer.json

@@ -18,7 +18,7 @@
     "require": {
         "php": "^7.1",
         "guzzlehttp/guzzle": "~6.0",
-        "illuminate/support": "5.7.* || 5.8.* || 6.*",
+        "illuminate/support": "5.7.* || 5.8.* || 6.* || 7.*",
         "symfony/dotenv": "^4.2"
     },
     "require-dev": {