How to convert 2D string list to 2D int list python?

How to convert a 2d string list in 2d int list? example:

>>> pin_configuration = [['1', ' 1', ' 3'], ['2', ' 3', ' 5'], ['3'], ['4', ' 5'], ['5', ' 1'], ['6', ' 6'], ['7']]

>>> to [[1,1,3], [2,3,5], [3], [4,5], [5,1], [6,6], [7]]