Tell Python from where to import dependencies
A user had huge problems installing Briar GTK as .debs, because they also had installed previous versions of
briar_wrapper with pip. They installed the latest versions of all .debs, but nevertheless got a warning due to an outdated version of
briar_wrapper. Instead of using the newer .deb version in /usr/lib/python3/dist-packages/briar_wrapper, Briar GTK imported
briar_wrapper from /usr/local/lib/python3.8/dist-packages/briar_wrapper, which was the old version from pip.