Update Container Version(s)

[www-signal-fyi]

Updating:
python:3.7-buster

[codara-ai-code-review]

Potential issues, bugs, or flaws:

1. /Dockerfile
   • The change in the FROM instruction to pin the Python base image to a specific digest is a good practice for reproducibility, but it's important to ensure that this digest is regularly updated to include any important security patches or updates. Additionally, consider extending the image digest to cover the entire python:3.7-buster-slim image, including the parent layers, for a more comprehensive guarantee of image immutability.