Sphinx 6 breaks version selection menu

[adamjstewart]

When upgrading to Sphinx 6, we found that the version selection menu no longer works. For example, compare the following versions of our documentation and attempt to change the version you are looking at:

• v0.3.1 (built with Sphinx 5.0.2): https://torchgeo.readthedocs.io/en/v0.3.1/
• v0.4.0 (built with Sphinx 6.1.3): https://torchgeo.readthedocs.io/en/v0.4.0/

I further narrowed this down by testing both Sphinx 5.3.0 and 6.0.0 and found that 6.0.0 is where the issue was first introduced.

Also, even before that, the placement of the version selection menu was off, and jumped to the other side of the screen for some reason.