feat: allow guzzle 7.x

Author: pashamesh

composer.json

@@ -4,7 +4,7 @@
     "type": "library",
     "require": {
         "ext-json": "*",
-        "guzzlehttp/guzzle": "^6.2"
+        "guzzlehttp/guzzle": "^6.2|^7.0"
     },
     "autoload": {
         "psr-4": {