In resolver, allow source distributions with static metadata, but no requires-python compatibility

[charliermarsh]

The following fails to resolve under --python 3.11, because interpreters-pep-734 has no wheels, and it requires at least Python 3.13, ostensibly to get the metadata -- however, the package has static metadata in the pyproject.toml, so we should actually be able to resolve it without issue:

[project]
requires-python = ">=3.11"

[project.optional-dependencies]
sub = [
    "interpreters-pep-734>=0.4.1; python_version ~= '3.13'",
]