fix: update poster_url on remote review Update activity

on_update was ignoring posterUrl from the AP note, so remote instances
never got the poster even after receiving the Update.

crates/adapters/activitypub/src/review_handler.rs

@@ -153,6 +153,7 @@ impl ApObjectHandler for ReviewObjectHandler {
                 obj.rating.min(5),
                 obj.comment.as_deref(),
                 obj.watched_at.naive_utc(),
+                obj.poster_url.as_deref(),
             )
             .await?;