Apt package missing bash bindings

Hello,

I usually install powerline via pip, but today I tried to install the python3-powerline package instead.

I noticed that the bindings for bash and/or shell weren't part of the package: https://gist.github.com/mattysweeps/245f7f62f51e27e965a3456ff9c5e0b9

This isn't a major concern since I can always install powerline via pip, but it was a surprise and the documentation for installing powerline with apt doesn't mention this hurdle.

I'm not familiar with how the python3- debian packages work, so sorry if this is intentional.