[FIX] base: count attachment correctly

Since _search return a query object, we cannot slice it. So we listify
it.

Thanks to XMO and RYV for their very valuable input.

closes odoo/odoo#122589

X-original-commit: 2e51b638232aff90405f318abb849f8b8db38496
Signed-off-by: Masereel Pierre <pim@odoo.com>

odoo/addons/base/models/ir_attachment.py

@@ -579,7 +579,7 @@ class IrAttachment(models.Model):
             more_ids = self.with_context(need=need)._search(
                 domain, offset + len(all_ids), limit, order, access_rights_uid,
             )
-            result.extend(more_ids[:limit - len(result)])
+            result.extend(list(more_ids)[:limit - len(result)])
 
         return self.browse(result)._as_query(order)