RTD builds cleanly.
RTD fails. Error
Config file validation error
Config validation error in build.os. Expected one of (ubuntu-22.04, ubuntu-24.04, ubuntu-26.04, ubuntu-lts-latest), got type str (ubuntu-20.04). Double check the type of the value. A string may be required (e.g. "3.10" instead of 3.10)
Expected behavior
RTD builds cleanly.
Actual behavior
RTD fails. Error
Code to reproduce the behavior
See https://app.readthedocs.org/projects/mdanalysis-sphinx-theme/builds/33426160/