github import: https://repo.packagist.org/p/subrion/cms.json not found

When importing github, get https://repo.packagist.org/p/subrion/cms.json not found error:
```
$ python manage.py import github
Importing data from github
Traceback (most recent call last):
File "/opt/vulnerablecode/vulnerabilities/management/commands/import.py", line 110, in _import_data
ImportRunner(importer, batch_size).run(cutoff_date=cutoff_date)
File "/opt/vulnerablecode/vulnerabilities/import_runner.py", line 89, in run
process_advisories(data_source)
File "/usr/local/lib/python3.8/contextlib.py", line 75, in inner
return func(*args, **kwds)
File "/opt/vulnerablecode/vulnerabilities/import_runner.py", line 116, in process_advisories
advisory_batches = chain(data_source.updated_advisories(), data_source.added_advisories())
File "/opt/vulnerablecode/vulnerabilities/importers/github.py", line 178, in updated_advisories
return self.batch_advisories(self.process_response())
File "/opt/vulnerablecode/vulnerabilities/importers/github.py", line 258, in process_response
self.set_version_api(ecosystem)
File "/opt/vulnerablecode/vulnerabilities/importers/github.py", line 213, in set_version_api
self.set_api(self.collect_packages(ecosystem))
File "/opt/vulnerablecode/vulnerabilities/importers/github.py", line 175, in set_api
asyncio.run(self.version_api.load_api(packages))
File "/usr/local/lib/python3.8/asyncio/runners.py", line 44, in run
return loop.run_until_complete(main)
File "/usr/local/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
return future.result()
File "/opt/vulnerablecode/vulnerabilities/package_managers.py", line 68, in load_api
await asyncio.gather(
File "/opt/vulnerablecode/vulnerabilities/package_managers.py", line 345, in fetch
resp = await session.request(method="GET", url=endpoint)
File "/usr/local/lib/python3.8/site-packages/aiohttp/client.py", line 625, in _request
resp.raise_for_status()
File "/usr/local/lib/python3.8/site-packages/aiohttp/client_reqrep.py", line 1000, in raise_for_status
raise ClientResponseError(
aiohttp.client_exceptions.ClientResponseError: 404, message='Not Found', url=URL('https://repo.packagist.org/p/subrion/cms.json')
Failure to import data from github. Continuing...
```

Hope url to be fixed or removed...