edited get_username because nickname from legacy is not unique

apps/transfer/serializers/account.py

@@ -24,10 +24,11 @@ class UserSerializer(serializers.ModelSerializer):
         return data
 
     def create(self, validated_data):
+        # использовать get_or_create
         User.objects.create(**validated_data)
 
     def get_email_confirmed(self, obj):
         return True
 
     def get_username(self, obj):
-        return obj["nickname"]
+        return obj["email"]