If the Platypush setup.py is found in the current directory, then use
that directory as the base for the new image.
Otherwise, clone the repo on the fly and build the image from there.
All the latest versions of Alpine, Debian, Ubuntu and Fedora now require
`--break-system-packages` when installing packages via `pip` outside of
a virtual environment, even if it's within a container.
Fabio Manganiello