Exploration of using `uv` for managing dependencies in all of our charms

[mvlassis]

Context

As part of the base upgrades task, we could potentially also change our dependency management to use uv.

What needs to get done

• Look into how we will replace the requirements.in, requirements.txt files with the structure that is used by uv.
• Determine whether that is beneficial for the team.

Definition of Done

• We have decided on whether we will use uv for our dependencies, and if so, we know the best way to achieve this