Remove django-stubs dependency from production code

rest_registration/exceptions.py

@@ -1,11 +1,11 @@
 from typing import Any, Dict, List, Optional, Union
 
 from django.utils.translation import gettext_lazy as _
-from django_stubs_ext import StrOrPromise
 from rest_framework.exceptions import APIException as _APIException
 from rest_framework.settings import api_settings
 
 from rest_registration.settings import registration_settings
+from rest_registration.utils.types import StrOrPromise
 
 _DetailType = Union[StrOrPromise, List[str], Dict[str, List[str]]]
 

rest_registration/utils/types.py

@@ -1,6 +1,8 @@
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
+    from django_stubs_ext import StrOrPromise
+
     # mypy uses typing_extensions by default (Py 3.8); when importing from typing
     # one will get the following error message in mypy:
     #
@@ -13,3 +15,4 @@
         from typing import Literal
     except ImportError:
         from typing_extensions import Literal  # noqa: F401
+    StrOrPromise = str