Cast client id to avoid PG error

If someone send a malformated client_id when trying to authenticate using the API we got a 500 if wallabag use postgres because the request send a string instead of an integer.

src/Wallabag/ApiBundle/Repository/ClientRepository.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Wallabag\ApiBundle\Repository;
+
+use Doctrine\ORM\EntityRepository;
+
+class ClientRepository extends EntityRepository
+{
+    public function findOneBy(array $criteria, array $orderBy = null)
+    {
+        if (!empty($criteria['id'])) {
+            // cast client id to be an integer to avoid postgres error:
+            // "invalid input syntax for integer"
+            $criteria['id'] = (int) $criteria['id'];
+        }
+
+        return parent::findOneBy($criteria, $orderBy);
+    }
+}