borderpad accepts a tuple for separate x/y padding

The borderpad parameter used for placing anchored artists (such as inset axes) now accepts a tuple of (x_pad, y_pad).

This allows for specifying separate padding values for the horizontal and vertical directions, providing finer control over placement. For example, when placing an inset in a corner, one might want horizontal padding to avoid overlapping with the main plot's axis labels, but no vertical padding to keep the inset flush with the plot area edge.

Example usage with inset_axes():

ax_inset = inset_axes(
    ax, width="30%", height="30%", loc='upper left',
    borderpad=(4, 0))