Cannot always select older versions from docs switcher

[leehart]

Once a recent version has been selected from the switcher, e.g. version 11.0.0, the older versions cannot be seen or selected.

Scrolling down does not reveal the older versions, which includes the "dev" (latest) version.

• E.g. https://malariagen.github.io/malariagen-data-python/v11.0.0/index.html

• Upstream third-party issue Version switcher extends beyond the page when there are a lot of items pydata/pydata-sphinx-theme#1774