[Freedombox-pkg-team] plinth is marked for autoremoval from testing

[Debian testing autoremoval watch]

plinth 19.0 is marked for autoremoval from testing on 2019-03-14

It (build-)depends on packages with these RC bugs:
920027: python3-persistent: ships headers in /usr/include/python3.7/
920029: python3-zope.proxy: ships header in /usr/include/python3.7/
921423: letsencrypt: /var/log/letsencrypt gets wiped on transitional package purge