Merge pull request #96 from shweshi/analysis-JDMneQ

Apply fixes from StyleCI

Author: shweshi

src/Exceptions/FetchException.php

@@ -9,7 +9,7 @@ class FetchException extends \Exception
     public function __construct(
         $message = '',
         $code = 0,
-        \Throwable $previous = null,
+        ?\Throwable $previous = null,
         $data = []
     ) {
         parent::__construct($message, $code, $previous);