Bug integrating with DRF

I followed the steps in https://graphene-django-murali.readthedocs.io/en/latest/rest-framework.html

```
class Produto(models.Model):
nome = models.CharField(max_length=50, unique=True)
tamanho = models.IntegerField(null=True, blank=True)
preco = models.DecimalField(max_digits=8, decimal_places=2)
quantidade = models.IntegerField()

def __str__(self):
return self.nome

class Meta:
verbose_name = "Produto"
verbose_name_plural = "Produtos"

class ProdutoType(DjangoObjectType):
class Meta:
model = Produto

class ProdutoSerializer(serializers.ModelSerializer):
class Meta:
model = Produto
fields = ("id", "nome", "tamanho", "preco", "quantidade")

class QueryDefinition(graphene.ObjectType):
all_produtos = graphene.List(ProdutoType)

def resolve_all_produtos(self, info, **kwargs):
return Produto.objects.all()

class ProdutoSerializerMutation(SerializerMutation):
class Meta:
serializer_class = ProdutoSerializer

class Mutations(graphene.ObjectType):
create_or_update_produto = ProdutoSerializerMutation.Field()

schema = graphene.Schema(mutation=Mutations, query=QueryDefinition)
```

The project runs but when i'm testing i can create and list objects normally but in update it not accept id value

```
mutation {
createOrUpdateProduto(input:{id: 6, nome: "a", tamanho: 1, preco: 0, quantidade:0}){
id
nome
}
}

{
"errors": [
{
"message": "Argument \"input\" has invalid value {id: 6, nome: \"a\", tamanho: 1, preco: 0, quantidade: 0}.\nIn field \"id\": Unknown field.",
"locations": [
{
"line": 2,
"column": 31
}
]
}
]
}
```

If i put only update in model_operations inside ProdutoSerializerMutation it complains that id is unknown field but if i take if out it complains that it should have an id

My versions:
Django==3.1.4
djangorestframework==3.12.2
graphene==2.1.8
graphene-django==2.13.0
graphql-core==2.3.2

Start with the rest-framework.html integration guide linked in the issue and reproduce the create and update mutations using the shown ProdutoSerializerMutation configuration. Trace how model_operations and the input id are handled, then verify that an update accepts the identifier without making the create flow invalid.

Written by the indexing model from the issue text.