Migrate to use Python 3 and newer Pelican
This is just an issue to track the progress of the Python 3 migration.
On the branch migrate/py3 I can locally build the site, but I needed to disable the i18n plugin for now to do it.
For reference, I'm using
Python 3.6.8 and
The site builds ok, so I suppose if @schumaml could get builds on that branch live on static.gimp.org we can start asking folks to spot-check pages. Once we're feeling fairly confident that nothing is seriously amiss, we can consider rolling it out live.