Decimal quantities in requisition_line

[clemens-msupply]

Changing the pack_size to a float size, the requisition quantity column need to be updated as well:

table! {
    requisition_line (id) {
        id -> Text,
        requisition_id -> Text,
        item_link_id -> Text,
        item_name -> Text,
        requested_quantity -> Integer,
        suggested_quantity -> Integer,
        supply_quantity -> Integer,
        available_stock_on_hand -> Integer ,
        average_monthly_consumption -> Integer,
        snapshot_datetime -> Nullable<Timestamp>,
        approved_quantity -> Integer,
        approval_comment -> Nullable<Text>,
        comment -> Nullable<Text>,
    }
}