[FIX] l10n_in: Fix tax grouping key

tax grouping key from base and tax line that will be used as a key to group taxes together
so both functions must have the same dictionary key. (you can check comment here https://github.com/odoo/odoo/blob/13.0/addons/account/models/account_move.py#L412)

here we have three key (product_id,product_uom_id,quantity) in _get_tax_grouping_key_from_base_line
and only one key (product_id) in _get_tax_grouping_key_from_tax_line

so we get wrong tax calculation

now we remove that extra key(product_uom_id, quantity) because we don't need group by these key values.

closes odoo/odoo#41340

X-original-commit: a758e5eace55bad0c11f8a27ba83e8367d293487
Signed-off-by: Josse Colpaert <jco@openerp.com>

addons/l10n_in/models/account_invoice.py

@@ -42,8 +42,6 @@ class AccountMove(models.Model):
         res = super()._get_tax_grouping_key_from_base_line(base_line, tax_vals)
         res.update({
             'product_id': base_line.product_id.id,
-            'product_uom_id': base_line.product_uom_id.id,
-            'quantity': base_line.quantity,
         })
         return res