Support uv natively #162
Description
In #133 I proposed building venvs with UV, i.e. uv venv/uv pip.
This is a speed-up for classic workflows using requirements.txt but does not allow thx to be used with uv as a project tool, as uv uses uv.lock natively or the the PEP-751 pylock.toml.
Instead of independent requirements files, these formats support a single file, with package selections parameterised by extras and dependency groups.
The existence of dependency groups and uv's default of installing the dev group also make it desirable to support different dependency groups per job, or none, though this could come later.