Matplotlib: Rotate label on a vertical slider

So, in this link you can find an MRE that generates a plot with sliders, and one of them is vertical. The link is from matplotlib's docs.

Now, the question is the following: You can see that the vertical slide has a label, however the label is shown horizontally. How can I put it vertically?

Just in case, the reason why I want to achieve this is because what I am actually trying to do is generate n sliders with a function. These must be vertical and with little separation between them. The problem is that this causes severe overlapping on their labels, so I prefer to have shorter sliders but with the labels placed vertically.

It's preferrable if I don't have to create a new Slider class from either Slider or SliderBase classes, but I am okey with that if necessary.

Thank you in advance.