[Python-buildbots] Extended downtime for kloth-* workers

To ensure the interested parties are aware, my workers (kloth-win11, kloth-win64 and kloth-win7) will be offline for an extended (and undetermined) period of time. I'll be moving cross-country (US) so it will be several weeks until I have a place.

This shouldn't be too disruptive to coverage as David also has workers for these areas.

Thanks.

-- Jeremy Kloth