post_version.py: drop incorrect conf.py changes

This needs to be done in the mesa3d.org repo; see
https://gitlab.freedesktop.org/mesa/mesa3d.org/-/merge_requests/19

Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5928>
2 files changed