Use of deprecated function for Google Cloud Storage

The root cause is an upstream Google Storage bug. The quick fix is to change the use of the deprecated function. The better fix is to move to using geddit which already contains the fix.

See traceback:

Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/gunicorn/arbiter.py", line 589, in spawn_worker
    worker.init_process()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/workers/gthread.py", line 92, in init_process
    super().init_process()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/workers/base.py", line 134, in init_process
    self.load_wsgi()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/workers/base.py", line 146, in load_wsgi
    self.wsgi = self.app.wsgi()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/app/base.py", line 67, in wsgi
    self.callable = self.load()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/app/wsgiapp.py", line 58, in load
    return self.load_wsgiapp()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/app/wsgiapp.py", line 48, in load_wsgiapp
    return util.import_app(self.app_uri)
  File "/usr/local/lib/python3.7/site-packages/gunicorn/util.py", line 359, in import_app
    mod = importlib.import_module(module)
  File "/usr/local/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/src/app/authenticatorproject/wsgi.py", line 16, in <module>
    application = get_wsgi_application()
  File "/usr/local/lib/python3.7/site-packages/django/core/wsgi.py", line 12, in get_wsgi_application
    django.setup(set_prefix=False)
  File "/usr/local/lib/python3.7/site-packages/django/__init__.py", line 19, in setup
    configure_logging(settings.LOGGING_CONFIG, settings.LOGGING)
  File "/usr/local/lib/python3.7/site-packages/django/conf/__init__.py", line 79, in __getattr__
    self._setup(name)
  File "/usr/local/lib/python3.7/site-packages/django/conf/__init__.py", line 66, in _setup
    self._wrapped = Settings(settings_module)
  File "/usr/local/lib/python3.7/site-packages/django/conf/__init__.py", line 157, in __init__
    mod = importlib.import_module(self.SETTINGS_MODULE)
  File "/usr/local/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 953, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/src/app/authenticatorproject/settings/__init__.py", line 8, in <module>
    from .base import *  # noqa: F401, F403
  File "/usr/src/app/authenticatorproject/settings/base.py", line 33, in <module>
    'EMAIL_HOST', 'EMAIL_HOST_PASSWORD', 'EMAIL_HOST_USER', 'EMAIL_PORT',
  File "/usr/local/lib/python3.7/site-packages/externalsettings/loader.py", line 107, in load_external_settings
    optional_settings=optional_settings
  File "/usr/local/lib/python3.7/site-packages/externalsettings/loader.py", line 121, in _fetch_external_settings
    _dict_deep_update(loaded_settings, _import_settings_url(url))
  File "/usr/local/lib/python3.7/site-packages/externalsettings/loader.py", line 176, in _import_settings_url
    return yaml.safe_load(_fetch_url(url))
  File "/usr/local/lib/python3.7/site-packages/externalsettings/loader.py", line 197, in _fetch_url
    return _fetch_storage_url(components)
  File "/usr/local/lib/python3.7/site-packages/externalsettings/loader.py", line 237, in _fetch_storage_url
    return blob.download_as_string()
  File "/usr/local/lib/python3.7/site-packages/google/cloud/storage/blob.py", line 1521, in download_as_string
    _DOWNLOAD_AS_STRING_DEPRECATED, PendingDeprecationWarning, stacklevel=2
TypeError: expected string or bytes-like object