No null fields

Let's see if this fixes the errors

src/artscrolling/__init__.py

···
     )
 
 
[e-mail]("/xrpc/app.bsky.feed.getFeedSkeleton")
[e-mail]("/xrpc/app.bsky.feed.getFeedSkeleton", response_model_exclude_none=True)
 async def get_feed_skeleton(
     skeleton_query: t.Annotated[FeedSkeletonQuery, Query()],
 ) -> FeedSkeleton:

src/artscrolling/models.py

···
 
     did: Did
     feeds: list[FeedGeneratorFeed]
-    links: FeedGeneratorLinks | None = (
-        None  # TODO: Do not include links: null if not present?
-    )
+    links: FeedGeneratorLinks | None = None
 
 
 class FeedSkeletonPost(BaseModel):