Fixed an important bug where request callback was never applied to request !

src/ApiRepository.php

@@ -85,7 +85,7 @@ class ApiRepository extends \Ulmus\Repository
 
         $request = $this->compileRequestParameters($request, $attribute);
 
-        $this->callApiRequestCallback($request, $attribute);
+        $request = $this->callApiRequestCallback($request, $attribute);
 
         $response = $this->launchRequest($request, $attribute);