uv support

[jorenham]

This introduces (some) support for uv.

Because python-utils uses requires python>3.8, the progressbar2 one also had to be changed from >=3.8 to >3.8

some other potential uv-related improvements that aren't included in this PR are:

• tox-uv
• using uv in the ci workflows (astral-sh/setup-uv)
• migrate the project.optional-dependencies to dependency-groups (technically a breaking change)
• replace the setuptools build system with e.g. hatch, for e.g. PEP 639 support
• a uv badge in the README.rst

[wolph]

Thank you for the addition, seems to work flawlessly!