Fixed an error with PHP 8.1

src/Config.php

@@ -126,7 +126,7 @@ class Config implements ConfigInterface
      */
     public function getApiToken()
     {
-        return $this->apiVersion;
+        return $this->apiToken;
     }
 
     /**
@@ -134,7 +134,7 @@ class Config implements ConfigInterface
      */
     public function setApiToken($apiToken)
     {
-        $this->apiVersion = $apiToken;
+        $this->apiToken = $apiToken;
 
         return $this;
     }