- fix issue "TypeError: Expected instance of hashes.HashAlgorithm."

- removed backend because PBKDF2HMAC no longer needs or uses it

Author: DelboyJay

django_cryptography/conf.py

@@ -1,15 +1,13 @@
 from typing import Any, Dict
 
 from appconf import AppConf
-from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives.kdf import pbkdf2
 from django.conf import settings
 from django.utils.encoding import force_bytes
 
 
 class CryptographyConf(AppConf):
-    BACKEND = default_backend()
     DIGEST = hashes.SHA256()
     KEY = None
     SALT = "django-cryptography"
@@ -22,16 +20,14 @@ def configure_salt(self, value: Any) -> bytes:
         return force_bytes(value)
 
     def configure(self) -> Dict[str, Any]:
-        backend = self.configured_data["BACKEND"]
-        digest = self.configured_data["DIGEST"]
+        digest = self.configured_data["DIGEST"]()
         salt = self.configured_data["SALT"]
         # Key Derivation Function
         kdf = pbkdf2.PBKDF2HMAC(
             algorithm=digest,
             length=digest.digest_size,
             salt=salt,
             iterations=30000,
-            backend=backend,
         )
         self.configured_data["KEY"] = kdf.derive(
             force_bytes(self.configured_data["KEY"] or settings.SECRET_KEY)