Request handler patch.

Changelog excerpt:
- Added a guard to the request handler's request method to fail if
  curl_init doesn't exist.

src/Request.php

@@ -108,7 +108,7 @@ public function request(string $URI, $Params = [], int $Timeout = -1, array $Hea
     {
         /** Guard. */
         if (!function_exists('curl_init')) {
-            return false;
+            return '';
         }
 
         /** Test channel triggers. */