migrate github importer to importer improver model

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

Author: TG1999

vulnerabilities/importers/__init__.py

@@ -20,8 +20,9 @@
 #  VulnerableCode is a free software code scanning tool from nexB Inc. and others.
 #  Visit https://github.com/nexB/vulnerablecode/ for support and download.
 from vulnerabilities.importers import alpine_linux
+from vulnerabilities.importers import github
 from vulnerabilities.importers import nginx
 
-IMPORTERS_REGISTRY = [nginx.NginxImporter, alpine_linux.AlpineImporter]
+IMPORTERS_REGISTRY = [nginx.NginxImporter, alpine_linux.AlpineImporter, github.GitHubAPIImporter]
 
 IMPORTERS_REGISTRY = {x.qualified_name: x for x in IMPORTERS_REGISTRY}