fix: replace double with single quotes

Author: fschmtt

src/Http/Client.php

@@ -68,7 +68,7 @@ public function request(string $method, string $path = '', array $options = []):
 
     public function isAuthorized(): bool
     {
-        return $this->tokenStorage->retrieveAccessToken()?->isExpired((new DateTime())->add(new \DateInterval("PT30S"))) === false;
+        return $this->tokenStorage->retrieveAccessToken()?->isExpired((new DateTime())->add(new \DateInterval('PT30S'))) === false;
     }
 
     private function authorize(): void