Add DjangoUnionType to init

Author: that-one-arab

graphene_django/__init__.py

@@ -1,12 +1,13 @@
 from .fields import DjangoConnectionField, DjangoListField
-from .types import DjangoObjectType
+from .types import DjangoObjectType, DjangoUnionType
 from .utils import bypass_get_queryset
 
 __version__ = "3.2.2"
 
 __all__ = [
     "__version__",
     "DjangoObjectType",
+    "DjangoUnionType",
     "DjangoListField",
     "DjangoConnectionField",
     "bypass_get_queryset",