text: Title: strawberry_django_plus.filters.filter makes fields required by default?!
  Body: When using `strawberry_django_plus.filters.filter` instead of `strawberry_django.filter`, the annotated fields appear to be required, i.e. activated by default in GraphiQL, and using `deprecation_reason` causes the schema to validate:
  
  > ❌ Required input field FooFilter.bar_status cannot be deprecated.
  
  ```python
  @filter(models.Foo)
  class FooFilter:
      bar_status: str = gql.django.field(deprecation_reason="use … instead")
  ```
  
  I've seen that `| None` can be used with the annotation to make it optional, but I think it should be optional by default.
  
  code ref: https://github.com/blb-ventures/strawberry-django-plus/blob/273d906ac7191f5eb073e1bf18b96cd1268466f9/strawberry_django_plus/filters.py#L65-L92