Migrate the project to UV (closes #104)

[kocielnik]

Ref. #104

Is this not gonna break deployments to Google App Engine? =========================================================

It seems UV is already supported:

Python development on Google Cloud just got a lot faster and easier as
I am excited to announce that uv now comes pre-installed in Cloud Shell!

-- Jack Wotherspoon,
https://medium.com/google-cloud/lightning-fast-python-on-google-cloud-a8ee4438a977

Other platforms support UV too. Vercel's app deployment engine already requires UV:

Vercel now uses uv, a fast Python package manager written in Rust, as
the default package manager during the installation step for all Python
builds.

This change makes builds 30-65% faster and adds support for more
dependency formats. In addition to requirements.txt or Pipfile, projects
can now declare dependencies with a uv.lock or pyproject.toml file.

-- Ricardo Gonzalez and Luke Phillips-Sheard,
https://vercel.com/changelog/python-package-manager-uv-is-now-available-for-builds-with-zero

Is this tool stable?

Yes. In my experience, UV was able to do everything Poetry does, and more.

In addition, is lighter (a single binary), and much faster - comparison here: https://github.com/astral-sh/uv).

When asked about the best package manager for today's Python, another Python developer says:

For most Python projects in 2026, uv is the right default.

‒ Tim Hopper, "Python Developer Tooling Handbook",
https://pydevtools.com/handbook/explanation/which-python-package-manager-should-i-use/

He says that for any project able to migrate easily (this appears to be one of them), it shouldn't hurt to switch to UV.

About Tim Hopper:

Tim Hopper is an AI research engineer at Spotify and a CPython
contributor.

– https://pydevtools.com/about/

What if it does not work for this particular project? =====================================================

To switch back to Poetry we would only need to revert the migration commit.