Add lint workflow

[ThirVondukr]

Closes #600

This PR adds:

Package Manager

https://docs.astral.sh/uv/
Tool to manage project dependencies, with support for pyproject.toml (https://peps.python.org/pep-0621/)

Mypy

https://github.com/python/mypy
Static type checker

Ruff

https://docs.astral.sh/ruff/
Linter and formatter

workflows/lint.yaml uses python 3.12, I don't think this should be an issue as long as target versions are configured properly for ruff and mypy.

[ThirVondukr]

Latest versions of mypy and ruff only support python 3.8 and 3.7 respectively 🤔

[d0tiKs]

Latest versions of mypy and ruff only support python 3.8 and 3.7 respectively 🤔

Comparing to novnc compatibility you mean ?

What versions of Python does Ruff support?
Ruff can lint code for any Python version from 3.7 onwards, including Python 3.13.
[...]
Ruff is installable under any Python version from 3.7 onwards.

And for mypy it seems to be : Requires: Python >=3.9
https://pypi.org/project/mypy/

[ThirVondukr]

Comparing to novnc compatibility you mean ?

Yes, currently latest release of websockify on pypi states it's compatible with 3.4 and on master branch it's 3.6.
As for mypy - it's possible to use slightly older version, I think that's already handled in uv.lock:

[package.dev-dependencies]
dev = [
    { name = "mypy", version = "0.971", ..., marker = "python_full_version < '3.7'" },
    { name = "mypy", version = "1.4.1", ..., marker = "python_full_version == '3.7.*'" },
    { name = "mypy", version = "1.14.1", ..., marker = "python_full_version == '3.8.*'" },
    { name = "mypy", version = "1.15.0", ..., marker = "python_full_version >= '3.9'" },
]

only quite early version of ruff (0.0.17) supports 3.6 though

[ThirVondukr]

Also it seems like only ~3% of downloads are for python 3.6 and 3.7 https://pypistats.org/packages/websockify