How can we restrict the Quantity field to accept only whole numbers (no decimals)?

Summary:

We are procuring 3 laptops, which is a non‑divisible item. The quantity must always be a whole number.
However, while creating the requisition, the system allows decimal quantities and is auto‑splitting the quantity across distributions (for example, showing 1.2 and 1.8). This scenario is not valid because laptops cannot be partially ordered.
Please note:

This is an Expense Item
We do not use Inventory
The Inventory module is not implemented

Because this is an expense‑based purchase and not inventory‑controlled, quantity should still be restricted to whole numbers, especially for items like laptops where fractional quantities are not possible.