FEATURE make user email nullable

packages/mock_server/fixtures/users.json

@@ -154,7 +154,6 @@
         {
             "id": 15,
             "username": "test",
-            "email": "test2@test.com",
             "password": "**********",
             "first_name": "",
             "last_name": "",

packages/paperless_api/lib/src/models/user_model.dart

@@ -16,7 +16,7 @@ class UserModel with _$UserModel {
   const factory UserModel.v3({
     @HiveField(0) required int id,
     @HiveField(1) required String username,
-    @HiveField(2) required String email,
+    @HiveField(2) String? email,
     @HiveField(3) String? firstName,
     @HiveField(4) String? lastName,
     @HiveField(5) DateTime? dateJoined,