Install Python dependencies in virtual environment in Docker images to satisfy PEP 668; replace apt-get with apt

[matthew-li]

Context

• The Ubuntu Docker image pulled for Apple Silicon appears to have adopted PEP 668, producing the below error when attempting to install Pip requirements in the absence of a virtual environment.

  error: externally-managed-environment
  
  × This environment is externally managed
  ╰─> To install Python packages system-wide, try apt install
      python3-xyz, where xyz is the package you are trying to
      install.
  
      If you wish to install a non-Debian-packaged Python package,
      create a virtual environment using python3 -m venv path/to/venv.
      Then use path/to/venv/bin/python and path/to/venv/bin/pip. Make
      sure you have python3-full installed.
  
      If you wish to install a non-Debian packaged Python application,
      it may be easiest to use pipx install xyz, which will manage a
      virtual environment for you. Make sure you have pipx installed.
  
      See /usr/share/doc/python3.11/README.venv for more information.
  
  note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
  hint: See PEP 668 for the detailed specification.

Changes

• Added a virtual environment to the app-config and app-base images.
• Prepended the binary directory of the virtual environment to PATH in these images so that the environment does not need to be explicitly sourced.
• Replaced apt-get calls with apt (newer, more user-friendly).

How to Test

• Ensure that the Docker build succeeds on both Intel (tested by me) and Apple Silicon.
• Ensure that Django commands (e.g., python manage.py shell) can be run in child containers without sourcing the virtual environment.

Notes

• It appears that, on Intel, Python 3.10 is installed, but on Apple Silicon, Python 3.11 is.

[matthew-li]

Thanks @helbashandy. Merging.