[FIX] point_of_sale: typo in `pos.config.settings` (wrong model inheritance)
[FIX] point_of_sale: typo in `pos.config.settings` (wrong model inheritance)

This fixes an error message preventing a non-system-manager user to edit the
Point of sale settings.

syci/OCB,optima-ict/odoo,syci/OCB,laslabs/odoo,stephen144/odoo,sysadminmatmoz/OCB,laslabs/odoo,Elico-Corp/odoo_OCB,dfang/odoo,hip-odoo/odoo,microcom/odoo,dfang/odoo,ygol/odoo,laslabs/odoo,storm-computers/odoo,hip-odoo/odoo,sysadminmatmoz/OCB,laslabs/odoo,hip-odoo/odoo,Elico-Corp/odoo_OCB,storm-computers/odoo,optima-ict/odoo,syci/OCB,storm-computers/odoo,hip-odoo/odoo,bplancher/odoo,stephen144/odoo,Elico-Corp/odoo_OCB,optima-ict/odoo,sysadminmatmoz/OCB,laslabs/odoo,ygol/odoo,hip-odoo/odoo,Elico-Corp/odoo_OCB,stephen144/odoo,Elico-Corp/odoo_OCB,stephen144/odoo,sysadminmatmoz/OCB,optima-ict/odoo,storm-computers/odoo,ygol/odoo,optima-ict/odoo,dfang/odoo,ygol/odoo,dfang/odoo,optima-ict/odoo,laslabs/odoo,syci/OCB,sysadminmatmoz/OCB,bplancher/odoo,storm-computers/odoo,sysadminmatmoz/OCB,stephen144/odoo,microcom/odoo,hip-odoo/odoo,bplancher/odoo,ygol/odoo,syci/OCB,syci/OCB,ygol/odoo,microcom/odoo,microcom/odoo,dfang/odoo,microcom/odoo,bplancher/odoo,storm-computers/odoo,bplancher/odoo,sysadminmatmoz/OCB,microcom/odoo,ygol/odoo,dfang/odoo,stephen144/odoo,bplancher/odoo,Elico-Corp/odoo_OCB