Dropdown menu to switch between docs versions doesn't work

[HealthyPear]

Describe the problem

The feature comes with the new PyData Sphinx Theme and is described here.
It is important to have it for when we'll leave third-party services like readthedocs, which do this automatically.

To Reproduce

Go to the built docs and click on the blue button in the upper-right corner.

Expected behavior

The drop-down menu should activate and (right now) it should show 2 versions: latest (development version) and v0.5.0, but it shows only latest.
The very beginning of the drop-down menu is visible but it's like cut...

Screenshots

Additional context

It could be either a bug in the implementation or it could be related to the same problem that causes #191 .

[HealthyPear]

Even though there was definitely a typo before, after merging #196 it still doesn't work as expected

[HealthyPear]

OK now it works (I don't know why it did with a certain delay after the latest build process, but anyway...)

The are still 2 caveats:

• since in v0.5.0 there was already this bug, it is now possible to go from "dev" to "v0.5.0 (stable)", but not possible to go back (still it can be done using readthedocs menu on the bottom right). This will work as intended from the next release (v0.5.1) on any platform.
• in "dev" mode (so locally) this doesn't seem to work yet