[FIX] Correct floating number comparison for min_quantity orderpoint in scheduler

Fix basic floating point math issue in procurement scheduler when comparing
current quantity with orderpoint minimum quantity. In certain cases floating
point comparison could result in e.g 400.0 < 400.0 == True due to typical
floating point comparison issues, as Odoo doesn't use Decimal types where the
issue doesn't exist.
Use float_compare helper to solve this with floating point type.
Indeed, the only errors will be through machine errors after summing (so HALF-UP will do) as the terms in the calculation for qty have been rounded already, but even then it is good to do a rounding.