Removed unused imports

src/pretix/base/forms/__init__.py

@@ -1,9 +1,7 @@
 import copy
 import logging
-import os
 
 from django import forms
-from django.conf import settings
 from django.core.files import File
 from django.core.files.storage import default_storage
 from django.core.files.uploadedfile import UploadedFile