chore: use dep groups

[henryiii]

This is a suggestion if you like it. It makes uv run pytest work out of the box (or uv run python, or uv run python -m unitest, etc). And to check benchmarking, you can do pip install -e. --group=benchmark.

[cpburnz]

I wasn't aware of dependency groups. Thanks.

Quick question: is the "dev" group required for uv, or was that more of an example to define dev dependencies?

[henryiii]

uv will install a group named dev by default, which means you can support uv run without any uv specific configuration.

[cpburnz]

It looks like pytest>=8 works with Python 3.9 and my usage, so I'm just reducing the required version, and merging them into the "dev" group.