Update Dockerfile to install python libraries in two steps, needed to run then needed for dev work

[the-other-james]

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[dragonejt]

Per the comment from @asgibson in #156 :

environment_dev.yml includes Black and Pylint. Did we want those required for the container?

If the dockerfile is just used for running OnAIR in production, I don't think we need black and pylint (the dev dependencies) to be installed in the docker image. I can change the Dockerfile to just reference the non-dev dependencies. The usual usage of black and pylint is as packages within a conda environment or python virtual environment. Docker containers are usually meant to just have the necessary dependencies to actually run the software.

If we do want to keep dev dependencies in the Dockerfile, I can also so what the original issue asks. Are we now installing based off of the requirements-*.txt files and no longer from the environment_*.yml ones?

Also, is it worth adding a GitHub action to build the docker image and make sure that works on each PR/push? That doesn't seem to exist currently.