Invalid version range in `apache_httpd` and `gentoo` advisory

[keshav-space]

We should not create version range using empty constraint.

'Cannot create AffectedPackage with invalid or unknown range: {'package': {'type': 'apache', 'namespace': '', 'name': 'httpd', 'version': '', 'qualifiers': '', 'subpath': ''}, 'affected_version_range': 'vers:apache/', 'fixed_version_range': None, 'introduced_by_commit_patches': [], 'fixed_by_commit_patches': []} with error:
Traceback (most recent call last):
  File "/app/vulnerabilities/importer.py", line 564, in from_dict
    VersionRange.from_string(affected_range) if affected_range else None
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/univers/version_range.py", line 139, in from_string
    raise ValueError(f"{vers!r} specifies no version range constraints.")
ValueError: 'vers:apache/' specifies no version range constraints.

[saisharan0103]

vulnerabilities/importer.py:from_dict is the part I would inspect first: the failing input has affected_version_range set to vers:apache/, so the empty constraint is reaching VersionRange.from_string(). For a PR, I would start by filtering or normalizing constraint-less vers: ranges before constructing AffectedPackage. The regression test should cover apache/httpd and gentoo advisory data that produces an empty range and assert import skips or clears that range without raising.