Updated BearerAuthorizationHeader __constructor

$token argument default value is '' (empty string)

Author: francerz

Diff for: src/headers/BearerAuthorizationHeader.php

@@ -5,7 +5,8 @@
 class BearerAuthorizationHeader extends AbstractAuthorizationHeader
 {
     private $token;
-    public function __construct(string $token)
+
+    public function __construct(string $token = '')
     {
         $this->token = $token;
     }