FIX] hr_payroll: fix payroll rules using a BrowableObject.sum().
FIX] hr_payroll: fix payroll rules using a BrowableObject.sum().

Since commit edcb318; using a python rule that uses the 'sum' function on a BrowsableObject was resulting in a UserError. Courtesy of jaredkipe

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