Added unauthorized exception message

Author: Frankisgek

src/Client.php

@@ -251,7 +251,7 @@ protected function handleRequestError(ResponseInterface $response)
         }
 
         if ($response->getStatusCode() == 401 || $response->getStatusCode() == 403) {
-            throw new UnauthorizedException();
+            throw new UnauthorizedException((string) $response->getBody());
         }
 
         if ($response->getStatusCode() == 400) {

src/Exceptions/UnauthorizedException.php

@@ -4,5 +4,13 @@
 
 class UnauthorizedException extends \Exception
 {
-    //
+    /**
+     * Create a new exception instance.
+     *
+     * @param string $message
+     */
+    public function __construct(string $message = '')
+    {
+        parent::__construct($message);
+    }
 }