fix black errors

Signed-off-by: Tushar Goel <tushar.goel.dav@gmail.com>

Author: TG1999

vulnerabilities/importers/nginx.py

@@ -20,6 +20,8 @@
 #  VulnerableCode is a free software tool from nexB Inc. and others.
 #  Visit https://github.com/nexB/vulnerablecode/ for support and download.
 
+import dataclasses
+import datetime
 from typing import Iterable
 import logging
 
@@ -38,6 +40,7 @@
 from vulnerabilities.importer import VulnerabilitySeverity
 from vulnerabilities.improver import Inference
 from vulnerabilities.improver import Improver
+from vulnerabilities.helpers import nearest_patched_package
 from vulnerabilities.models import Advisory
 from vulnerabilities.package_managers import GitHubTagsAPI
 from vulnerabilities.package_managers import Version