--------------------
Add support for piping `StrawberryUnion` and `None` when annotating types.
For example:
python
strawberry.type
class Cat:
name: str
strawberry.type
class Dog:
name: str
Animal = strawberry.union("Animal", (Cat, Dog))
strawberry.type
class Query:
animal: Animal | None This line no longer triggers a TypeError
Contributed by [Yossi Rozantsev](https://github.com/Apakottur) [PR #1540](https://github.com/strawberry-graphql/strawberry/pull/1540/)