convert to uv

[kornpow]

I've started using uv for python projects and it has made running python in various environments so much better.

I did a quick conversion to uv for you to check out.

One thing that changes is it removes the tkinter dependency. As far as I can tell from my research, tkinter is usually bundled in with python, and not installed using python package management. Either by doing sudo apt install python3-tkinter or all of the python installations uv can install has tkinter bundled: uv python install 3.11.

Generally even though it was an optional dependency, having tkinter defined was causing me lots of headaches. But let me know what you think.

This PR also adds in ruff, which is a flake8 replacement from the same people as uv.

Here is an example of running ruff (with a time command to show how fast it runs):

$ time uv run ruff check --no-fix
...
...
...
0.03s user 0.03s system 96% cpu 0.057 total

Another thing to mention is this is how to run the GUI:

# EITHER
uv run stservo-gui
# OR
uv sync
. .venv/bin/activate
stservo-gui

Im jumping back and forth between my Mac laptop and my Raspberry Pi, and am able to successfully run the tool.