Failing CI builds of Impit for Python on `musllinux`

see e.g. https://github.com/apify/impit/actions/runs/18528661486. 

The source of this error seems to be the new docs-building dependencies, which the runner cannot install due to the missing `git` installation.

This might be connected to `uv sync`, trying to resolve the dependency versions, even for dependencies omitted with `--no-group`. This should be fixable with the `--frozen` parameter.