[FIX] stock: access error on stock.quant

Usecase to reproduce:
- Connect on demo user (inventory user)
- Go on product page and click on stat button for 'quantity on hand'

> AccessError on decimal.precision object

due to commit a1eb000c93
When the user click on 'report inventory' button it will garbage
collect the remaining quants without quantity. In order to do it,
it needs the precision rounding in order to have a rounding and do
not let quant without significant quantity.

closes odoo/odoo#34780

Signed-off-by: Simon Lejeune (sle) <sle@openerp.com>

addons/stock/models/stock_quant.py

@@ -443,7 +443,7 @@ class StockQuant(models.Model):
         this method is often called in batch and each unlink invalidate
         the cache. We defer the calls to unlink in this method.
         """
-        precision_digits = max(6, self.env.ref('product.decimal_product_uom').digits * 2)
+        precision_digits = max(6, self.sudo().env.ref('product.decimal_product_uom').digits * 2)
         # Use a select instead of ORM search for UoM robustness.
         query = """SELECT id FROM stock_quant WHERE round(quantity::numeric, %s) = 0 AND round(reserved_quantity::numeric, %s) = 0;"""
         params = (precision_digits, precision_digits)