top ticks not shown for last axes

[mdmould]

Using the option top_ticks=True does not add the ticks to the last (bottom right) panel, e.g.:

import numpy as np
import corner

fig = corner(np.random.normal(size = (10_000, 2)), top_ticks = True)

One can add it back in manually, e.g.,

fig.axes[-1].tick_params(
    axis = 'x', top = True, labeltop = True,
    rotation = fig.axes[-1].get_xticklabels()[0].get_rotation(),
)

but it'd be good to work as intended.