Add support for PEP 735 dependency groups

[edgarrmondragon]

What's the problem this feature will solve?

PEP 735 was recently accepted, so as package managers begin to implement it it'd be nice if Tox also had support for it.

Describe the solution you'd like

Similar to how extras are currently supported, maybe a new config option for dependency groups:

[testenv]
dependency-groups = test
commands = pytest tests

Alternative Solutions

Can't think of any 🤷‍♂️.

Additional context

• Feature Proposal: PEP 735 "Dependency Groups" Support pypa/pip#12963
• Support for PEP 735: Dependency Groups in pyproject.toml astral-sh/uv#8090
• Support PEP 735 – Dependency Groups in pyproject.toml python-poetry/poetry#9751
• https://github.com/sirosen/dependency-groups
• https://peps.python.org/pep-0735/