[SAC] Nextcloud.osgeo.org will be upgraded in the next 24 hrs

I plan to upgrade https://nextcloud.osgeo.org to 18.0.3 later today. Plans
detailed here - https://trac.osgeo.org/osgeo/ticket/2243

I don't expect there to be more than 1 hr downtime during the process.

I will send out another notice just before I start the upgrade.

Email me if this poses a problem for you.