fix: [security] blind SQL injection in searchAll

- As reported by Zigrin Security

src/Controller/InstanceController.php

@@ -38,6 +38,7 @@ class InstanceController extends AppController
         $searchValue = $this->request->getQuery('search');
         $model = $this->request->getQuery('model', null);
         $limit = $this->request->getQuery('limit', 5);
+        $limit = is_numeric($limit) ? $limit : 5;
         if (!empty($this->request->getQuery('show_all', false))) {
             $limit = null;
         }

src/Model/Table/InstanceTable.php

@@ -81,7 +81,7 @@ class InstanceTable extends AppTable
         return $statistics;
     }
 
-    public function searchAll($value, $user, $limit=5, $model=null)
+    public function searchAll($value, $user, int $limit=5, $model=null)
     {
         $results = [];
         $models = $this->seachAllTables;