Twincolorbar missing ticks
It seems that there is an issue with [twin ticks on the colorbar](https://docs.planetary-coverage.org/en/latest/trajectory/instrument/fovs.html#customize-the-colorbar), at least since the version `0.10.0`:
```python
fig = plt.figure(figsize=(12, 9))
ax = fig.add_subplot(projection=GANYMEDE)
ax.add_collection(janus_flyby.fovs(facecolors='alt',
vmin=500, vmax=10_000,
sort='dist', reverse=True))
ax.colorbar(vmin=500, vmax=10_000, label='alt', extend='max')
ax.twin_colorbar(label='JANUS pixel scale',
ticks=[25, 50, 75, 100, 125, 150],
format=janus_flyby.observer.ifov_cross_track * m_pix_ticks)
ax.set_title('JANUS footprints during 2G2 flyby (Feb. 13th 2032)');
```
This could be related to a matplotlib version upgrade.
The expected figure should look like this:
However, the issue is not present in MAJIS FOV example :thinking: in `1.0.0`:
issue