Provide more context when dependency collection fails for sdists

[woodruffw]

#349 demonstrates a need for this: when we call pip install some-sdist.tar.gz internally, it might fail if the distribution itself is broken or has an unreliable build system.

At the moment, we surface that with an uncontrolled exception, which makes the error appear as if it's within pip-audit and not the project's build:

Traceback (most recent call last):
  File "/app/.local/bin/pip-audit", line 8, in <module>
    sys.exit(audit())
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_cli.py", line 428, in audit
    for (spec, vulns) in auditor.audit(source):
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_audit.py", line 66, in audit
    for dep, vulns in self._service.query_all(specs):
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_service/interface.py", line 148, in query_all
    for spec in specs:
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_dependency_source/requirement.py", line 120, in collect
    for _, dep in self._collect_cached_deps(filename, reqs):
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_dependency_source/requirement.py", line 320, in _collect_cached_deps
    for req, resolved_deps in self._resolver.resolve_all(iter(req_values)):
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_dependency_source/interface.py", line 87, in resolve_all
    yield (req, self.resolve(req))
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_dependency_source/resolvelib/resolvelib.py", line 75, in resolve
    result = self.resolver.resolve([req])
  File "/app/.local/lib/python3.10/site-packages/resolvelib/resolvers.py", line 481, in resolve
    state = resolution.resolve(requirements, max_rounds=max_rounds)
  File "/app/.local/lib/python3.10/site-packages/resolvelib/resolvers.py", line 373, in resolve
    failure_causes = self._attempt_to_pin_criterion(name)
  File "/app/.local/lib/python3.10/site-packages/resolvelib/resolvers.py", line 213, in _attempt_to_pin_criterion
    criteria = self._get_updated_criteria(candidate)
  File "/app/.local/lib/python3.10/site-packages/resolvelib/resolvers.py", line 203, in _get_updated_criteria
    for requirement in self._p.get_dependencies(candidate=candidate):
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_dependency_source/resolvelib/pypi_provider.py", line 370, in get_dependencies
    return candidate.dependencies
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_dependency_source/resolvelib/pypi_provider.py", line 120, in dependencies
    self._dependencies = list(self._get_dependencies())
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_dependency_source/resolvelib/pypi_provider.py", line 102, in _get_dependencies
    deps: List[str] = self.metadata.get_all("Requires-Dist", [])
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_dependency_source/resolvelib/pypi_provider.py", line 95, in metadata
    self._metadata = self._get_metadata_for_sdist()
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_dependency_source/resolvelib/pypi_provider.py", line 163, in _get_metadata_for_sdist
    ve.create(ve_dir)
  File "/usr/local/lib/python3.10/venv/__init__.py", line 78, in create
    self.post_setup(context)
  File "/app/.local/lib/python3.10/site-packages/pip_audit/_virtual_env.py", line 106, in post_setup
    raise VirtualEnvError(f"Failed to install packages: {package_install_cmd}") from cpe
pip_audit._virtual_env.VirtualEnvError: Failed to install packages: ['/tmp/tmp3dhmfebg/bin/python', '-m', 'pip', 'install', '/tmp/tmpoec42g0s/uwsgi-2.0.20.tar.gz']

We should tweak this to surface the build's underlying error, along with some guidance suggesting that the error is probably not pip-audit's fault and should be reported downstream instead.