handle image attachments recursively

bookwyrm/activitypub/image.py

@@ -1,9 +1,11 @@
 ''' an image, nothing fancy '''
 from dataclasses import dataclass
+from .base_activity import ActivityObject
 
-@dataclass
-class Image:
+@dataclass(init=False)
+class Image(ActivityObject):
     ''' image block '''
     url: str
     name: str = ''
     type: str = 'Image'
+    id: str = ''