Replace faulty pip CLI option in Dockerfile (#991)
Replace faulty pip CLI option in Dockerfile (#991)

The provided Dockerfile contains the instruction

    RUN pip install --install-option="--prefix=/install" fava

which results in the following error during the Docker build process for
the latest version of the python:alpine image:

    /usr/local/lib/python3.8/site-packages/pip/_internal/commands/install.py:283: UserWarning: Disabling all use of wheels due to the use of --build-options / --global-options / --install-options.

The image build succeeds, but attempting to create a container with it
results in the following error:

    /bin/sh: fava: not found
beancount/fava,yagebu/fava,beancount/fava,beancount/fava,beancount/fava,aumayr/beancount-web,yagebu/fava,aumayr/beancount-web,beancount/fava,yagebu/fava,aumayr/beancount-web,yagebu/fava,yagebu/fava,aumayr/beancount-web