Uploading demos doesn't work in cloud env

[sentry-io]

Sentry Issue: WEB-V

InvalidResponse: ('Request failed with status code', 403, 'Expected one of', <HTTPStatus.OK: 200>)
(1 additional frame(s) were not displayed)
...
  File "/usr/local/lib/python3.6/site-packages/google/cloud/storage/blob.py", line 987, in _do_upload
    client, stream, content_type, size, num_retries, predefined_acl
  File "/usr/local/lib/python3.6/site-packages/google/cloud/storage/blob.py", line 781, in _do_multipart_upload
    response = upload.transmit(transport, data, object_metadata, content_type)
  File "/usr/local/lib/python3.6/site-packages/google/resumable_media/requests/upload.py", line 98, in transmit
    self._process_response(result)
  File "/usr/local/lib/python3.6/site-packages/google/resumable_media/_upload.py", line 110, in _process_response
    response, (http_client.OK,), self._get_status_code)
  File "/usr/local/lib/python3.6/site-packages/google/resumable_media/_helpers.py", line 93, in require_status_code
    status_code, u'Expected one of', *status_codes)

Forbidden: 403 POST https://www.googleapis.com/upload/storage/v1/b/teerace-web-media/o?uploadType=multipart: ('Request failed with status code', 403, 'Expected one of', <HTTPStatus.OK: 200>)
(15 additional frame(s) were not displayed)
...
  File "rest_framework/views.py", line 495, in dispatch
    response = self.handle_exception(exc)
  File "rest_framework/views.py", line 455, in handle_exception
    self.raise_uncaught_exception(exc)
  File "rest_framework/views.py", line 492, in dispatch
    response = handler(request, *args, **kwargs)
  File "api/v1/views.py", line 66, in post
    best_run.save()
  File "race/models.py", line 241, in save
    super().save(*args, **kwargs)

Forbidden: 403 POST https://www.googleapis.com/upload/storage/v1/b/teerace-web-media/o?uploadType=multipart: ('Request failed with status code', 403, 'Expected one of', <HTTPStatus.OK: 200>)