5.2.2 brings in important fix that is needed for wendelin.core 2:
https://github.com/zopefoundation/ZEO/pull/160

They say that `zodbpickle.binary` is now much more lightweight on CPython2:
https://github.com/zopefoundation/zodbpickle/blob/master/CHANGES.rst#200-2019-11-13

software/caddy-frontend implements all requirements and apache-frontend is
not tested neither developed except small fixes, so it's ok to keep it for
reference or some small work outside of official tree, as other developers
might have urge to use it.

*  Updates component/pureftpd url to 1.0.49 version because the one provided do not exist anymore (the 1.0.46 version exists now under the path [https://download.pureftpd.org/pub/pure-ftpd/releases/obsolete/pure-ftpd-1.0.46.tar.bz2](https://download.pureftpd.org/pub/pure-ftpd/releases/obsolete/pure-ftpd-1.0.46.tar.bz2))
*  Deletes explicit slapos.toolbox dependency because it's automatically installed by monitor stack