Doc: Version selector does not work as expected

[dbaston]

What is the bug?

Attempting to switch between versions of the documentation (e.g., "stable" to "latest") brings one to the top-level page instead of the corresponding page in the other version.

Steps to reproduce the issue

1. Navigate to https://gdal.org/en/stable/programs/gdal_calc.html
2. Using ReadTheDocs menu, set version to "latest"
3. URL in location bar is set to https://gdal.org/en/latest/

Versions and provenance

_

Additional context

No response

[rouault]

Probably a ReadTheDocs issue, as I can reproduce the same with https://proj.org . My memories is that it used to work