Updates dependency management

[helrond]

Brings dependency management in line with other apps:

• Adds dependabot config
• separates and updates requirements
• Uses pip-compile to manage secondary dependencies

Makes a few other changes to the app to accommodate updates, primarily to Django and DRF.

[p-galligan]

Generally looks good and has less verbosity.

However, I'm getting a warning on standing it up about the clam av virus definitions being out of date. Is that anything to be concerned about?

[helrond]

You'll get that warning if you don't build the container frequently. It's not something I'm worried about.