Include changes from #15040
This is a best-effort attempt to provide/update lower bounds on direct
dependencies in two groups: hard requirements, and test dependencies.
At the time of opening, I still see 7 test failing locally with an env
obtained with `uv sync --resolution=lowest-direct` which may indicate
that some updates are still needed (although it is not clear what
dependencies are causing the failures). It could also be a symptom of
*transitive* dependencies incompatibilities. In any case, this is still
much better than no explicit lower bounds at all.
The end goal is to enable testing downstream with `--resolution=lowest`.
To guide reviewers I've included small comments to justify my choice of
lower bounds. I simply commented "wheel" in places where I picked the
oldest version that has a compatible wheel on PyPI (in some cases, older
versions might still build from source, but relying on much more recent
versions of setuptools is more or less bound to break at some point).

If you're interested, I'd be happy to also setup a CI job to
systematically check that lower bounds are sound and up to date.