A food truck sells a few dishes. Its sales come as a grid: one row per day and one column per dish.
The owner wants to see each dish's share of that day's sales, so busy days and quiet days can be compared fairly. A dish's share on a day is its sales that day divided by the day's total sales.
Task: write daily_shares(sales) and return a grid of the same shape, as a list of lists, with every value turned into its share of its own day's total. Round each share to 3 decimal places.
Every day sold at least one dish, so no day's total is 0. Each row of the answer adds up to about 1.