[SAC] Wiki upgrade happening Friday

I'm planning to do the old-wiki -> new wiki (Debian 10 latest Media Wiki
install and MariaDb) this Friday.
Sometime late night US ET time.

Let me know if this poses a problem for you.

The domain once complete will still be https://wiki.osgeo.org

But I will take it down during the migration.

I don't expect more than 2 hrs downtime. Hopefully only one hour.