Try running:
python manage.py collectstatic
Does the test work now? If so, this might be the configuration causing a problem:
STATICFILES_STORAGE = 'whitenoise.django.GzipManifestStaticFilesStorage'
as of whitenoise v4 this will fail and you should use:
STATICFILES_STORAGE = 'whitenoise.storage.CompressedManifestStaticFilesStorage'
Related:
https://stackoverflow.com/a/32347324/2596187
Check out the Django documentation:
https://docs.djangoproject.com/en/1.11/ref/contrib/staticfiles/#django.contrib.staticfiles.storage.ManifestStaticFilesStorage.manifest_strict