Write method computeTemp, which computes and returns the new temperature for a given element of temps according to the following rules.
a. If the element is in the border of the array (in the first row or last row or first column or last column), the new temperature is the same as the old temperature.
b. Otherwise, the new temperature is the average (arithmetic mean) of the temperatures of the four adjacent values in the table (located above, below, to the left, and to the right of the element).
