[FIX] stock_picking_batch: compute properly scheduled time on batch

closes odoo/odoo#93920

Signed-off-by: Arnold Moyaux (arm) <arm@odoo.com>

addons/stock_picking_batch/models/stock_picking_batch.py

@@ -104,7 +104,8 @@ class StockPickingBatch(models.Model):
 
     @api.depends('picking_ids', 'picking_ids.scheduled_date')
     def _compute_scheduled_date(self):
-        self.scheduled_date = min(self.picking_ids.filtered('scheduled_date').mapped('scheduled_date'), default=False)
+        for rec in self:
+            rec.scheduled_date = min(rec.picking_ids.filtered('scheduled_date').mapped('scheduled_date'), default=False)
 
     @api.onchange('scheduled_date')
     def onchange_scheduled_date(self):