[FIX] account: invoice report: group also by sign, as it's use in query
[FIX] account: invoice report: group also by sign, as it's use in query

hip-odoo/odoo,hip-odoo/odoo,ygol/odoo,ygol/odoo,hip-odoo/odoo,dfang/odoo,dfang/odoo,hip-odoo/odoo,dfang/odoo,ygol/odoo,ygol/odoo,dfang/odoo,hip-odoo/odoo,dfang/odoo,ygol/odoo,ygol/odoo,dfang/odoo,ygol/odoo,hip-odoo/odoo